Endocrine · Full case

Hypothyroidism

NICE NG145

0.4–4.0Normal TSH range (mU/L)

1.6 mcg/kgStarting dose levothyroxine if <65 and no CVD (25–50 mcg if ≥65 or cardiac)

6–8 weeksRecheck TSH interval after dose change

TSH >10Subclinical: consider levothyroxine if TSH ≥10 on 2 tests 3 months apart (NICE NG145)

TSH 4–10Subclinical: individualise — symptoms, age, TPO antibodies, pregnancy

Trimester rangePregnancy TSH target — laboratory trimester-specific range or local protocol; prompt specialist advice

30 minLevothyroxine: take on empty stomach 30 min before food

4 hoursSeparate calcium, iron and antacids from levothyroxine — reduce absorption

📋 Clinical Stem — Hypothyroidism

A patient presents with fatigue, weight gain, cold intolerance, constipation, dry skin, or hair loss — or is found to have an elevated TSH on routine or targeted blood testing.

"Ms Sarah Brennan is a 42-year-old teacher who presents with a 4-month history of increasing fatigue, weight gain of 5 kg, feeling cold all the time, worsening constipation, dry skin, and thinning hair. She has been told she is 'probably depressed' and was recently started on sertraline by a locum GP without thyroid function tests being checked. She takes calcium carbonate 500 mg daily for osteoporosis prevention. She is not pregnant but is trying to conceive."

Hypothyroidism is one of the most commonly missed diagnoses in primary care. Symptoms are insidious, non-specific, and frequently attributed to depression, age, or lifestyle. The framework addresses: confirming the diagnosis (TSH + free T4), identifying the cause (Hashimoto's — TPO antibodies), safe initiation of levothyroxine, critical drug interactions, and special populations (pregnancy, cardiac, elderly).

Scenario A — Overt hypothyroidism TSH >10 + low free T4 + symptoms. Start levothyroxine 1.6 mcg/kg/day (nearest 25 mcg) if under 65 with no cardiovascular disease. Recheck TSH + free T4 in 6–8 weeks. Titrate in 25 mcg increments.

Scenario B — Subclinical hypothyroidism TSH 4–10 + normal free T4 ± symptoms. If TSH ≥10 on 2 tests 3 months apart: consider levothyroxine (NICE NG145). If TSH 4–10: individualise (symptoms, age, TPO antibodies, pregnancy plans). Two elevated TSH results required before treatment.

Scenario C — Hypothyroidism in pregnancy Raised TSH above the trimester-specific range. Prompt specialist/local pathway advice (NG145 excludes pregnancy; RCOG GTG76, 2025). Treatment thresholds depend on TSH, FT4, TPO-antibody status and trimester-specific ranges. Increase dose by 25–30% immediately when pregnancy confirmed.

Scenario D — Elderly / cardiac patient Start at 25–50 mcg OD (not the full weight-based dose). Titrate slowly (25 mcg steps; TSH from about 6 weeks after each change, about every 3 months until stable). Risk of precipitating angina or arrhythmia with too-rapid increase in cardiac patients.

Scenario E — Hashimoto's thyroiditis Elevated TPO antibodies + elevated TSH. Autoimmune cause. Associated with other autoimmune conditions (type 1 diabetes, coeliac, vitiligo, Addison's). Family history relevant. Higher risk of progression from subclinical to overt hypothyroidism.

Scenario F — Myxoedema coma Severe hypothyroidism + hypothermia + confusion + bradycardia + hypoventilation. Life-threatening emergency — 999 immediately. IV T4 (levothyroxine). ITU admission. Rare but must not be missed.

Steps:

Step 1

History Taking — Open Question First · Targeted Questions · ICE · Psychosocial Context

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Hypothyroidism history has two layers: the symptom picture (non-specific and easily attributed elsewhere) and the clinical context (risk factors, family history, drug causes, special populations). The classic symptom cluster — fatigue, weight gain, cold intolerance, constipation, dry skin, hair loss, bradycardia, slowed reflexes — often develops insidiously over months to years. Many patients have been labelled with depression, menopause, or IBS before thyroid disease is diagnosed. ICE in hypothyroidism must address the patient's existing diagnosis (often depression) and their understanding of what the thyroid does.

🎓 Consultation opener

"I can see from your notes that you've been feeling very tired recently and have been started on an antidepressant. Before we talk about that, I'd like to ask a few questions and check your thyroid — a small gland in your neck that controls your metabolism. Can you tell me more about how you've been feeling?"

Reference the existing information from the stem (fatigue, sertraline started) before asking open questions. This demonstrates preparation, saves time, and immediately builds rapport. In SCA, it gains a mark in the Global Skills domain before you have asked a single clinical question.

1A — Targeted questions: what changes management

Question	Why it matters	Changes what?
🟢 OPEN — always start here"Tell me more about how you've been feeling — when did things start to change, and what's been bothering you most?"	Hypothyroid symptoms are insidious — patients often struggle to identify a clear onset. The open question gathers the symptom cluster organically and allows the patient to describe the impact on their life (which provides the management context for ICE).	DDxPsychosocial
Fatigue pattern"Describe the tiredness — is it there all the time, or worse at certain times? Has it been getting worse gradually?"	Hypothyroid fatigue is typically constant, progressive, and not relieved by sleep — unlike depression (which is often worst in the mornings) or anaemia (which is worse with exertion). The gradual onset over months is characteristic. Diurnal variation absent in hypothyroidism helps distinguish from depression.Classic: "I've been progressively more tired over the past year — I can sleep 10 hours and still feel exhausted."	DDx
Weight change"Have you noticed weight gain despite not eating more — or weight loss?"	Unintentional weight gain (typically 2–5 kg) from reduced basal metabolic rate is a characteristic hypothyroid symptom. Weight loss with fatigue would point away from hypothyroidism towards hyperthyroidism, malignancy, or depression. Quantifying the weight gain and rate is clinically useful.In SCA: framing weight gain as a physiological consequence (reduced metabolism) rather than a lifestyle failing is important for the patient's emotional wellbeing and engagement with treatment.	DDxPsychosocial
Cold intolerance"Have you been feeling cold when others aren't — wearing extra layers, feeling cold to the touch?"	Reduced thermogenesis from low thyroid hormone is one of the most specific hypothyroid symptoms — patients feel cold even in warm environments. Distinguish from Raynaud's (cold extremities only) or anaemia (general cold but with pallor, exertional dyspnoea). Cold intolerance in a previously heat-tolerant individual is a red flag for hypothyroidism.A useful screen: "Do your family comment that you always feel cold to the touch?" — often more specific than self-reported cold intolerance.	DDx
Skin, hair and nails"Have you noticed your skin becoming dryer than usual, your hair thinning or falling out more than normal, or any changes in your nails?"	Dry coarse skin, brittle hair, and diffuse hair loss (including outer third of eyebrows — Hertoghe's sign) are classic hypothyroid signs. Hair loss is a particularly distressing symptom for many patients and often the first thing they notice. It is frequently attributed to stress, menopause, or nutritional deficiency rather than thyroid disease.	DDx
Mood and cognition"How has your mood been — any depression, low mood? And has your memory or concentration been affected?"	Hypothyroidism directly causes depression, cognitive slowing, and poor concentration through reduced cerebral metabolic activity. Many patients are treated for depression without thyroid function being checked — this is one of the most consequential diagnostic delays in primary care. Always check TFTs in new depression, especially in over-40s and in patients not responding to antidepressants.In this case: TFTs should have been checked before starting sertraline. Framing this gently is important — do not criticise the previous GP openly; focus on the current diagnostic opportunity.	DDxManagement
Constipation and bowel habit"How are your bowels — have things slowed down compared to normal?"	Reduced gut motility from low thyroid hormone is a common hypothyroid symptom, often presenting as the primary complaint. Hypothyroidism is one of the most commonly missed secondary causes of constipation — identifying it here may explain symptoms previously attributed to other causes.	DDxManagement
Voice changes, hoarseness"Has your voice changed — become huskier or deeper than it used to be?"	Hoarseness from myxoedematous infiltration of the larynx is a classic but often late sign of hypothyroidism. Voice change in a patient with other hypothyroid symptoms is highly specific. Also consider laryngeal malignancy if voice change is rapid or associated with other head/neck symptoms.	DDx
Pregnancy, fertility, menstrual changes"Are you currently pregnant or trying to conceive? Have your periods changed — heavier or more irregular?"	This is one of the most clinically urgent questions in hypothyroidism. Untreated hypothyroidism in pregnancy is associated with miscarriage, pre-eclampsia, stillbirth, and foetal neurodevelopmental delay. Any patient trying to conceive with elevated TSH requires urgent thyroid optimisation and referral. Menorrhagia (heavy periods) is a classic hypothyroid symptom from anovulatory cycles and coagulopathy.In SCA: this question is a specific mark if the scenario involves a woman of childbearing age. Missing pregnancy/fertility context in a hypothyroid case is a critical failure point.	UrgencyReferral
Drug history — amiodarone, lithium, interferon"What medications are you currently taking — including any for heart conditions, mood disorders, or antiviral treatments?"	Drug causes of hypothyroidism: amiodarone (contains 37% iodine — causes both hypo- and hyperthyroidism), lithium (blocks thyroid hormone release — hypothyroidism in up to 40% of long-term users), interferon-alpha, tyrosine kinase inhibitors. Also critical: calcium carbonate, iron and antacids reduce levothyroxine absorption — separate by about 4 hours (PPIs have variable effects; keep consistent and recheck after changes).In this case: patient takes calcium carbonate — this must be counselled to be taken 4 hours apart from levothyroxine, or it will significantly reduce levothyroxine absorption and result in treatment failure.	DDxManagement
Family history of thyroid disease"Has anyone in your family been diagnosed with a thyroid condition — over- or under-active thyroid, or autoimmune conditions?"	Hashimoto's thyroiditis (autoimmune hypothyroidism) has a strong familial component — first-degree relatives have approximately 5× increased risk. Family history of other autoimmune conditions (type 1 diabetes, coeliac, rheumatoid arthritis, vitiligo, Addison's disease) also increases risk. Positive family history lowers the TSH threshold for treatment consideration in subclinical cases.	DDxInvestigations
Previous neck surgery or radioiodine"Have you ever had any surgery to your neck or throat, or treatment with radioiodine?"	Post-thyroidectomy (total or partial) and post-radioiodine ablation are common causes of iatrogenic hypothyroidism. These patients require lifelong levothyroxine and are at risk of subtherapeutic dosing as requirements change with age, weight, and medication changes. Different management consideration — lifelong replacement vs autoimmune hypothyroidism which may fluctuate.	DDxManagement

1B — Red flags: must not miss

🚨

Red Flags

Red flag	Why dangerous	Action
Hypothermia + confusion + bradycardia + hypoventilation in known or suspected hypothyroidism	Myxoedema coma — life-threatening emergency. Mortality 25–60% even with treatment. Precipitated by cold exposure, infection, opioids, or sedatives in severely hypothyroid patient.	999 immediately
New hypothyroidism discovered in pregnancy or patient trying to conceive	Untreated hypothyroidism in pregnancy: miscarriage, pre-eclampsia, stillbirth, foetal neurodevelopmental impairment (irreversible). Urgency is disproportionate to TSH level — even mild elevation is dangerous.	Prompt specialist/local pathway advice (same day if pregnant)
Rapidly enlarging goitre or asymmetric thyroid swelling with hypothyroidism	While most goitres with hypothyroidism are Hashimoto's, rapidly enlarging or asymmetric swellings must exclude thyroid malignancy. Anaplastic thyroid cancer can present with rapid growth and hypothyroidism.	Urgent suspected thyroid cancer pathway referral
Severe symptomatic hypothyroidism with cardiac complications (pericardial effusion, bradycardia, cardiac failure)	Severe hypothyroidism can cause pericardial effusion, dilated cardiomyopathy, and profound bradycardia. Too-rapid levothyroxine replacement in this context can precipitate arrhythmia — requires hospital initiation.	Urgent cardiology review before starting levothyroxine

1C — ICE: Ideas · Concerns · Expectations

Patients presenting with hypothyroidism have almost always been told something else is causing their symptoms — depression, menopause, stress, age, or "just the way you are." Many have been treated for depression without response. The diagnosis of hypothyroidism often brings profound relief ("finally someone found the cause") but also concerns about lifelong medication, weight that might not return to normal, and whether the antidepressant they were started on was appropriate. ICE in hypothyroidism addresses all of these — and creates the therapeutic alliance that ensures levothyroxine is taken correctly.

💭 Ideas

"What was your own understanding of what was causing all this — the tiredness, weight gain, and feeling cold? Had anyone suggested what might be behind it?"

Many patients will say "I was told it was depression" or "I thought it was menopause." Others will have Googled their symptoms and already suspect thyroid disease. Establishing their existing model determines whether you are confirming a diagnosis they expect or reframing one they have already been given.

😟 Concerns

"Is there something you've been particularly worried about — whether about the diagnosis itself, or about taking medication long-term?"

Common concerns: Is this serious? Will I gain even more weight? Do I have to take tablets forever? Will the antidepressant I was started on make things worse? Will this affect my fertility? In SCA, identifying and addressing these concerns earns multiple Relating to Others domain marks.

🎯 Expectations

"What were you hoping would happen today — were you expecting a particular treatment, or hoping for an explanation?"

Patients with hypothyroidism often expect and want immediate symptom resolution. Managing this expectation is clinically important — symptoms improve gradually over 3–6 months on levothyroxine, not overnight. Setting this expectation prevents premature dose escalation based on ongoing symptoms rather than TSH level.

🎓 SCA Checkpoint — Step 1TasksRelating to OthersGlobal Skills

Key phrases that score

"Before we talk about the antidepressant, I'd like to check your thyroid — based on what you're describing, I think that may be the underlying cause."

"Are you currently pregnant or trying to conceive? This changes the urgency significantly."

"Do you take calcium tablets? — I'll need to explain something important about timing if I prescribe a thyroid tablet."

Deductions

Not asking about pregnancy/fertility — critical omission in a woman of childbearing age with new hypothyroidism
Not asking about calcium/iron/PPI — missing the most important levothyroxine interaction
Not addressing the antidepressant started without TFTs — must acknowledge and plan

🔴 Red

Pregnancy not asked. Drug history incomplete — calcium interaction missed. Antidepressant history not addressed. ICE absent.

🟠 Amber

Pregnancy asked but calcium interaction not explored. ICE partially explored — concern about lifelong medication not addressed.

🟢 Green

Pregnancy/fertility asked. Calcium and other interactions explored. Antidepressant history acknowledged with plan. ICE including lifelong medication concern and weight expectations addressed.

Step 2

Triage Engine — Emergency · Urgent · Routine

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Triage in hypothyroidism is driven by: is this a myxoedema emergency? Is the patient pregnant? Is there significant cardiac comorbidity requiring specialist initiation? Or is this routine primary care management? Most newly diagnosed hypothyroidism is managed entirely in primary care — but the exceptions (pregnancy, cardiac disease, myxoedema coma) are life-threatening and require immediate action.

🔴 Emergency / Urgent

999 or Same-Day Specialist

Act now

Myxoedema comaHypothermia + confusion + bradycardia + hypoventilation → 999; IV T4; ITU; mortality 25–60%
Hypothyroidism in pregnancy or trying to conceivePrompt specialist/local pathway advice (NG145 excludes pregnancy; RCOG GTG76, 2025); overt disease → start levothyroxine; targets use trimester-specific ranges
Severe hypothyroidism with cardiac complicationsPericardial effusion, bradycardia, cardiac failure → urgent cardiology review before initiating levothyroxine (too-rapid replacement precipitates arrhythmia)
Rapidly enlarging or asymmetric goitreSuspected thyroid cancer pathway referral — exclude anaplastic carcinoma

🟠 Refer / Specialist Input

Endocrine Referral

Weeks

Symptoms persist despite TSH in target range on adequate levothyroxine doseConsider T3/T4 combination (controversial; specialist decision only). Exclude poor absorption, adherence, interactions.
Elderly/frail with significant cardiac historyStart 25–50 mcg levothyroxine; cautious titration; cardiology if IHD makes titration impossible
Drug-induced hypothyroidism (amiodarone, lithium)Coordinate with the prescribing team; do not stop amiodarone without cardiology input
MEN2 or other hereditary thyroid syndrome suspectedGenetic counselling and specialist endocrine assessment

🟢 Routine

Primary Care Management

GP practice

Overt hypothyroidism (TSH >10, low free T4, symptoms) in otherwise well adultStart levothyroxine 1.6 mcg/kg/day (nearest 25 mcg) if under 65 with no CVD; recheck TSH + free T4 at 6–8 weeks; titrate in 25 mcg increments
Subclinical hypothyroidism (TSH 4–10, normal free T4) with symptoms or TPO antibodiesIndividualise; if treating, dose as for overt disease (by age and heart); review TSH from 6 weeks; if not treating, TSH annually if TPO-positive or other thyroid disease, otherwise every 2–3 years
Known hypothyroidism on stable levothyroxine — annual reviewAnnual TFTs; review dose if weight change, pregnancy status, or new drug interactions
Post-thyroidectomy replacement therapyLifelong levothyroxine; TSH target depends on cancer status (set by the thyroid cancer team for thyroid cancer; normal range for benign)

🎓 SCA Checkpoint — Step 2TasksGlobal Skills

Key phrases that score

"Given that you're trying to conceive, once I've confirmed the thyroid result I want to act on this the same day — an underactive thyroid can affect pregnancy significantly and we don't want to delay."

Deductions

Not recognising pregnancy/fertility as an urgent escalation trigger
Starting a full weight-based levothyroxine dose in an elderly or cardiac patient
Not recognising myxoedema features as a 999 emergency

Step 3

Do I Need This Examination?

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Examination in hypothyroidism confirms the clinical diagnosis, detects signs of severity, and identifies complications. No examination finding alone diagnoses hypothyroidism — but clinical signs increase the pre-test probability and guide urgency. The most important examination elements are: thyroid palpation, cardiovascular assessment, and delayed relaxation of deep tendon reflexes.

Examination	Why it matters	Finding that changes management	Changes management?
Thyroid palpation	Assess for goitre (enlarged thyroid — Hashimoto's produces a diffuse firm goitre), asymmetry, nodules, or tenderness (subacute thyroiditis). A bruit may be heard over a vascular goitre.Hashimoto's: diffuse, firm, rubbery goitre. Subacute thyroiditis: tender goitre. Malignancy concern: hard, fixed, asymmetric with cervical lymphadenopathy.	Hard fixed asymmetric mass → suspected thyroid cancer pathway referral. Tender goitre → subacute thyroiditis (usually self-limiting; may cause transient hypothyroidism). Diffuse goitre → consistent with Hashimoto's	YES — changes urgency
Cardiovascular examination — HR, BP, ECG	Hypothyroidism causes bradycardia, diastolic hypertension, raised cholesterol, and pericardial effusion. An ECG is important in moderate-severe hypothyroidism to detect low voltage complexes (pericardial effusion), bradycardia, or prolonged QTc (risk of arrhythmia). Rapid levothyroxine initiation in patients with significant cardiac disease can precipitate arrhythmia or angina.	Bradycardia + pericardial effusion signs → hospital referral before starting levothyroxine. Significant cardiac history → 25 mcg starting dose; ECG before initiation; cardiology input	YES — changes dose/urgency
Delayed deep tendon reflexes	Delayed relaxation of deep tendon reflexes (particularly ankle jerk) is a classic sign of hypothyroidism (not pathognomonic, and neither sensitive nor specific enough to diagnose alone) — the reflex fires normally but the relaxation is visibly slowed ("hung-up reflex"). This sign increases diagnostic specificity and confirms clinical hypothyroidism when TSH is equivocal.	Delayed reflexes support a more than mild picture — but overt disease is defined by a low FT4, which decides treatment. Normal reflexes + mildly elevated TSH → more likely subclinical; more caution before treating	YES — confirms diagnosis
Skin, hair, and face	Non-pitting periorbital oedema (myxoedema), dry coarse skin, pallor, sparse lateral eyebrows (Hertoghe's sign), macroglossia, and diffuse hair loss are classic hypothyroid signs. Myxoedema is not pitting (unlike cardiac oedema) — it is caused by glycosaminoglycan deposition, not fluid overload.	Marked periorbital oedema + other severe signs → consider hospital assessment for severe hypothyroidism. Pallor → check FBC (anaemia is common in hypothyroidism)	YES — assesses severity
Weight and BMI	Documents the weight gain attributed to hypothyroidism — important for tracking response to treatment (weight often partially normalises with adequate levothyroxine). Also identifies morbid obesity as an indication for higher levothyroxine doses (dosing is weight-based: approximately 1.6 mcg/kg/day).	Weight significantly elevated → levothyroxine dose target based on body weight calculation. Weight loss with hypothyroid symptoms → reassess diagnosis (consider hyperthyroidism alternating, subacute thyroiditis)	YES — informs dosing

🎓 SCA Checkpoint — Step 3TasksGlobal Skills

Key phrases that score

"I'd like to feel your thyroid gland today — it's just below your Adam's apple — and I'll also check your heart rate and reflexes, which can give us useful information about how your thyroid is affecting your body."

Deductions

Not examining the thyroid in a patient with hypothyroid symptoms — missing goitre, nodule, or malignancy signs
Not checking cardiovascular status before starting levothyroxine in an elderly or cardiac patient

Step 4

Do I Need This Investigation?

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TSH is the first-line investigation — alone it both diagnoses and guides treatment in most cases. Elevated TSH + low free T4 = overt hypothyroidism. Elevated TSH + normal free T4 = subclinical hypothyroidism. TPO antibodies identify Hashimoto's (autoimmune cause) and predict progression from subclinical to overt hypothyroidism.

Investigation	When to order and what it answers	Result that changes management
TSH (thyroid-stimulating hormone)	First-line and most sensitive test for thyroid dysfunction. A normal TSH virtually excludes hypothyroidism. Elevated TSH indicates the pituitary is "calling for" more thyroid hormone — the defining test for primary hypothyroidism. Must be confirmed on a second sample before treatment in subclinical cases (TSH <10).	TSH ≥10 on 2 tests 3 months apart: consider levothyroxine even without symptoms (NICE NG145). TSH 4–10: individualise. TSH normal: hypothyroidism excluded as cause of symptoms — investigate other causes.
Free T4 (freeT4 / fT4)	Ordered alongside TSH or when TSH is abnormal. Distinguishes overt hypothyroidism (elevated TSH + low free T4) from subclinical hypothyroidism (elevated TSH + normal free T4). Also useful for monitoring treatment adequacy (target mid-normal free T4 range).Note: free T3 is not routinely measured in primary care hypothyroidism assessment — it is ordered by specialists when assessing conversion disorders or combination T3/T4 therapy.	Low free T4 + elevated TSH → overt hypothyroidism; start levothyroxine. Normal free T4 + elevated TSH → subclinical; individualise treatment decision.
TPO antibodies (anti-thyroid peroxidase)	Identifies Hashimoto's thyroiditis as the cause of hypothyroidism. Positive TPO antibodies: (1) confirm autoimmune aetiology; (2) predict progression from subclinical to overt hypothyroidism (approximately 4%/year); (3) lower the treatment threshold in subclinical hypothyroidism; (4) raise awareness of associated autoimmune conditions (test according to symptoms and risk). Not required to initiate treatment — but useful prognostically.	Positive TPO + subclinical hypothyroidism → closer (annual) TSH monitoring; may favour a trial if symptomatic, but not by itself an indication when TSH <10; test for associated autoimmune conditions according to symptoms and risk. Positive TPO + normal TSH (euthyroid Hashimoto's) → annual TSH monitoring; no treatment yet.
FBC (full blood count)	Anaemia is common in hypothyroidism — normocytic anaemia from reduced erythropoietin, or macrocytic from associated vitamin B12 deficiency (particularly in Hashimoto's — associated with pernicious anaemia). Iron deficiency anaemia from menorrhagia is also common. FBC guides whether anaemia treatment is needed alongside levothyroxine.	Macrocytic anaemia + Hashimoto's → check B12 and folate; pernicious anaemia association. Iron deficiency anaemia → treat; note iron reduces levothyroxine absorption — take 4 hours apart. Normocytic anaemia → resolves with thyroid treatment alone.
Lipid profile (total cholesterol, LDL)	Hypothyroidism causes hypercholesterolaemia through reduced LDL receptor expression and decreased cholesterol clearance. Cholesterol should be checked and documented at diagnosis — it typically normalises with adequate levothyroxine treatment. If statin is considered for hypercholesterolaemia, always exclude and treat hypothyroidism first.	Elevated cholesterol with hypothyroidism → treat the thyroid first; reassess lipids once euthyroid where this will alter management. Do not delay indicated statin therapy solely because hypothyroidism is present.
Thyroid ultrasound	Indicated if: thyroid nodule(s) palpated; asymmetric or rapidly growing goitre; previous thyroid cancer or radiation history; suspicious features on examination. Not routinely required for typical Hashimoto's hypothyroidism diagnosed on TSH + TPO antibodies alone.Ultrasound in Hashimoto's typically shows: heterogeneous echogenicity, pseudonodules, increased vascularity — characteristic pattern that confirms autoimmune thyroiditis.	Nodule(s) detected → risk stratify using ACR TI-RADS or BTA U-classification; fine needle aspiration if high-risk features. Normal ultrasound in suspected Hashimoto's → reassures no structural cause; management unchanged.

🎓 SCA Checkpoint — Step 4TasksGlobal Skills

Key phrases that score

"I'm going to check your TSH — that's the main control hormone — and your free T4, which tells us whether the thyroid itself is producing enough. I'll also check for antibodies that would tell us if this is an autoimmune cause."

Deductions

Ordering free T3 as a first-line investigation — not routine in primary care hypothyroidism
Not checking lipids — hypothyroidism-related hypercholesterolaemia should be documented before considering statins

Step 5

Reaching a Diagnosis & DDx — Explained in Plain Language

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Explaining hypothyroidism in plain language requires making the thyroid's role in metabolism concrete and understandable. The "thermostat" analogy is the most effective: "Your thyroid is like the thermostat that controls your metabolism — it sets the speed at which your body works. When it's underactive, everything slows down: your metabolism, your bowels, your thinking, your heart rate." This one analogy explains fatigue, weight gain, constipation, cold intolerance, and cognitive slowing simultaneously.

🗣️ Diagnosis in Plain Language

"Your blood tests confirm that your thyroid gland is underactive. The thyroid is like the body's thermostat — it controls how fast your metabolism runs. When it's underactive, everything slows down: your energy, your digestion, your ability to keep warm, your mood, and even your thinking. This explains every symptom you've been having — the fatigue, weight gain, constipation, feeling cold, hair thinning, and the low mood. Importantly, this is not depression — or at least not the primary cause. I think the antidepressant you were started on recently may not have been the right first step, because the root cause is the thyroid. The good news is that this is very treatable with a simple tablet called levothyroxine — it replaces the hormone your thyroid should be making. Once your thyroid levels are right, most of your symptoms should improve significantly over the next 3 to 6 months."

💬 Addressing common patient concerns

"Will I have to take this tablet forever?"
"Most people with autoimmune hypothyroidism — which is what this appears to be — do need to take it long-term. The good news is that it's a simple once-daily tablet with very few side effects when the dose is right, and many people feel dramatically better once they're on the right dose. We'll monitor your blood tests regularly to make sure we keep it optimised."

"Will the weight come off once I start the tablet?"
"It often does improve — you may lose 2–3 kg once your metabolism returns to normal. However, I want to be honest: the thyroid replacement usually helps with the metabolic component, but if other factors like diet and activity are contributing, those will still need attention. I don't want to promise a transformation that isn't certain — but the metabolic contribution from the thyroid should improve."

"What about the antidepressant — should I stop it?"
"I wouldn't stop it abruptly without a plan — that needs careful thought. Once your thyroid levels are treated and normalised, we can review your mood again and decide together whether the sertraline is still needed. Many people find that their mood improves significantly with the thyroid treatment alone. Let's give it 3 months and see."

A — Primary care diagnosis and management

Hashimoto's thyroiditis (autoimmune)

Most common cause (70–80%). TPO antibodies positive. May fluctuate. Associated with other autoimmune conditions. Lifelong levothyroxine in most cases.

Post-thyroidectomy or post-radioiodine

Iatrogenic — lifelong replacement mandatory. Dose requirements may change with age. TSH target depends on indication (set by the thyroid cancer team if thyroid cancer, normal range for benign).

Iodine deficiency (rare in UK)

Endemic hypothyroidism from dietary iodine deficiency. More common in pregnancy and in populations avoiding iodised salt and dairy. Resolves with adequate iodine.

B — Drug-induced / Specialist input

Amiodarone-induced hypothyroidism

TSH elevation in patient on amiodarone (37% iodine). Do NOT stop amiodarone without cardiology — can precipitate life-threatening arrhythmia. Levothyroxine prescribed alongside.

Lithium-induced hypothyroidism

Up to 40% of long-term lithium users develop hypothyroidism. Coordinate with psychiatry before modifying lithium. Levothyroxine prescribed alongside ongoing lithium in most cases.

Subclinical hypothyroidism (TSH 4–10)

Individualise treatment — consider symptoms, TPO antibodies, age, pregnancy plans. Two elevated TSH results required before treatment. If not treating: TSH annually if TPO-positive or other features of thyroid disease, otherwise every 2–3 years.

C — Emergency / Urgent

Myxoedema coma

Severe hypothyroidism + hypothermia + confusion + bradycardia. 999. IV levothyroxine. ITU. Mortality 25–60%. Precipitants: cold exposure, infection, opioids.

Hypothyroidism in pregnancy

TSH above the trimester-specific range. Prompt specialist/local pathway advice and joint obstetric–endocrine care. Thresholds depend on TSH, FT4, TPO-antibody status and trimester-specific ranges. Foetal neurodevelopment at risk.

🎓 SCA Checkpoint — Step 5TasksRelating to Others

Key phrases that score

"Your thyroid is like the body's thermostat — when it's underactive, everything slows down. That explains the fatigue, weight gain, constipation, and the low mood."

"This is very treatable — and I believe treating the thyroid is the priority here, rather than the antidepressant."

Deductions

Not addressing the antidepressant started without TFTs — needs acknowledgement and plan
Promising complete weight normalisation — overpromising leads to loss of therapeutic trust
Not checking understanding after explanation

🔴 Red

Antidepressant not addressed. No thermostat analogy or equivalent. Overpromises on weight loss. Understanding not checked.

🟠 Amber

Correct diagnosis explained but antidepressant issue not sensitively handled. Weight expectations not explicitly managed. Understanding not checked.

🟢 Green

Thermostat analogy used. All symptoms linked to thyroid. Antidepressant addressed sensitively with clear plan. Honest weight expectation. Understanding checked.

Step 6

If Referral Is Needed

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Most hypothyroidism is managed entirely in primary care. Referral to endocrinology is needed for: pregnancy, persistent symptoms despite adequate TSH, drug-induced hypothyroidism requiring specialist coordination, or consideration of T3/T4 combination therapy.

Indication	Urgency	GP does before referral	Must NOT do
Hypothyroidism in pregnancy or TTC	Same-day urgent	Check TSH + free T4 urgently; overt disease → start levothyroxine while referral is processed; seek prompt specialist/local pathway advice (NG145 excludes pregnancy; RCOG GTG76, 2025); targets use laboratory trimester-specific ranges	Do not wait for specialist appointment before starting levothyroxine — the foetal neural development risk is immediate; do not apply non-pregnant TSH ranges in pregnancy — use laboratory trimester-specific ranges or the local obstetric/endocrine protocol
Symptoms persist despite TSH in normal range	Routine endocrine	First exclude: poor adherence, drug interactions (calcium, iron, PPIs all reduce absorption), dose too low based on weight, T4 to T3 conversion disorder. Document TSH consistently in normal range over 6–12 months. Review all medications.	Do not start T3 (liothyronine) in primary care without specialist endocrine input — T3 therapy is controversial and has cardiac risk
Amiodarone-induced hypothyroidism	Routine with cardiology coordination	Do not stop amiodarone without cardiology input; start levothyroxine if symptomatic or TSH >10; inform cardiologist of thyroid status; arrange joint monitoring	Never stop amiodarone without cardiology — risk of fatal arrhythmia; the hypothyroidism is managed alongside ongoing amiodarone, not by stopping it
Rapidly enlarging goitre or suspicious nodule	Suspected thyroid cancer pathway referral	Document examination findings; arrange thyroid ultrasound; continue levothyroxine treatment while awaiting specialist assessment	Do not reassure that a goitre is "just Hashimoto's" if there are new or rapidly changing structural features — malignancy must be excluded

Step 7

Management — Expectation · Goals · Lifestyle · Drug Cards · Psychosocial · Follow-Up · Safety-Netting

▲collapse

Levothyroxine is one of the most prescribed drugs in UK primary care — yet it is also one of the most commonly suboptimally managed. The key principles are: start low in elderly/cardiac patients, titrate in 25 mcg increments every 6–8 weeks, take on an empty stomach 30 minutes before food, separate from calcium/iron/antacids by about 4 hours, aim for a TSH within the reference range (not routinely the lower half — NICE NG145), and never titrate by symptoms alone — always recheck TSH before changing dose. In SCA, demonstrating knowledge of the interaction profile and the 6–8 week rechecking window earns specific Tasks domain marks.

7A — Address the patient's expectation first

🤝

Validate → explain → negotiate — in that order

Validate — name their expectation

Most patients expect to start a tablet and feel better quickly. Many are also frustrated that the antidepressant was started without checking the thyroid. Both of these expectations deserve direct acknowledgement before the clinical plan.

"You've been struggling for months and I completely understand the frustration — particularly that this wasn't picked up earlier. I want to put that right today."

Explain — share your clinical reasoning

The response to levothyroxine is gradual — symptoms improve over 3–6 months, not days. Setting this expectation prevents premature dose escalation based on ongoing symptoms. The thermostat analogy explains why it takes time: the body needs to readjust all its systems to a higher metabolic rate.

"The tablet works by gradually turning up the thermostat — your body has been running slow for months and it takes time for everything to recalibrate. Most people start feeling better within 4–6 weeks, but the full benefit takes 3–6 months."

Negotiate — offer something concrete today

Give the prescription today with specific counselling on timing. Book the 6–8 week blood test appointment before the patient leaves. Address the calcium interaction immediately — this is actionable today and prevents treatment failure.

"I'm going to prescribe this today — and the most important thing about taking it correctly is timing: take it on an empty stomach, 30 minutes before breakfast, and your calcium tablet at a completely different time — lunchtime or evening. I'm booking your blood test for 6 weeks."

Key principle: Correct levothyroxine timing counselling is the single most important practical instruction you can give. The patient who takes levothyroxine at the same time as their calcium supplement will have significantly reduced absorption and will feel no better — and may be labelled as "treatment-refractory" when in fact they are simply taking it incorrectly.

7B — Treatment goals

Treatment goals

TSH within the laboratory reference range (NICE NG145) Free T4 in mid-normal range Resolution of fatigue, cold intolerance, constipation, dry skin Mood normalisation — review antidepressant at 3 months Cholesterol normalisation without statin Weight partial normalisation (metabolic component) Pregnancy: trimester-specific TSH range — prompt specialist advice if trying to conceive Annual TFT monitoring when stable

Motivational language

"Every symptom you've been struggling with — the tiredness, the weight, the low mood, the constipation, the feeling cold — all of these have the same root cause. One tablet, taken correctly, addresses all of them at once."

"This is one of the most satisfying conditions to treat in general practice — when the thyroid levels are right, most people feel dramatically better. I want that for you."

7C — Non-medication management

Lifestyle measures support but do not replace levothyroxine in overt hypothyroidism. However, they are clinically relevant: dietary selenium supports thyroid peroxidase enzyme function; iodine sufficiency is essential; physical activity reduces the metabolic consequences of hypothyroidism during the titration period; stress management reduces HPA axis cortisol, which blunts T4 to T3 conversion.

⏰

Levothyroxine Timing

Take fasting, 30 min before breakfast; consistent time daily

Mechanism

Levothyroxine absorption is significantly reduced by food (particularly high-fibre and calcium-rich foods), coffee, and certain medications. An empty stomach maximises absorption. Consistency of timing improves TSH stability and reduces dose variation.

Practical

Take levothyroxine first thing in the morning — before getting up if possible — with a full glass of water. Wait 30 minutes before breakfast. Set a phone alarm if helpful. Bedtime dosing is an evidence-based alternative for those who cannot take it fasting in the morning.

Consistent fasting administration improves levothyroxine bioavailability by up to 40% vs with food

⚠️

Drug Interaction Management

Separate calcium, iron, antacids by about 4 hours; PPIs — keep consistent

Mechanism

Calcium carbonate, calcium citrate, ferrous sulphate/fumarate, and PPIs (especially omeprazole) all reduce levothyroxine absorption by 20–40%. Cholestyramine, sucralfate, and antacids also interfere. This is the most common cause of apparent treatment failure in primary care.

Practical

This patient takes calcium carbonate daily. Specific instruction: levothyroxine at 7am before breakfast; calcium carbonate with lunch or at bedtime — minimum 4 hours apart. Write this down for the patient and document it in the notes as a counselling point.

Correct separation from calcium/iron/antacids can restore TSH to target without needing a dose increase

🥗

Iodine Sufficiency

Adequate dietary iodine; avoid excessive seaweed or supplements

Mechanism

Iodine is required for thyroid hormone synthesis. In the UK, iodine deficiency is rare but emerging (particularly in vegans who avoid dairy). Excessive iodine supplementation (seaweed, high-dose iodine supplements) can paradoxically worsen Hashimoto's by triggering immune activation (Wolff-Chaikoff effect).

Practical

Normal UK diet with dairy provides adequate iodine. Vegetarians/vegans: consider iodine-fortified foods or low-dose supplement (150 mcg/day — not kelp-based which has variable high iodine content). Avoid high-dose iodine supplements entirely in Hashimoto's.

Adequate dietary iodine maintains optimal T4 synthesis alongside levothyroxine replacement

🏃

Physical Activity

Gentle, consistent activity during titration period

Mechanism

Hypothyroidism reduces cardiac output and muscle metabolism, making vigorous exercise difficult. During the titration period, gentle consistent activity (walking, swimming) maintains cardiovascular fitness and mental wellbeing without overloading an underperforming cardiac system.

Practical

Start with 20–30 minute daily walks; build up as energy improves. Avoid pushing through severe fatigue — this is physiological, not lack of effort. As TSH normalises, energy and exercise tolerance typically improve significantly.

Consistent gentle activity during treatment improves mood, maintains muscle mass, and supports metabolic recovery

🧠

Mental Wellbeing During Treatment

Manage expectations; recognise improving vs persistent depression

Mechanism

Hypothyroid-driven depression typically improves with thyroid treatment alone. However, it may take 3–6 months to resolve fully. If mood is not improving at 3 months despite TSH in target range, primary depression may be coexisting and antidepressant review is warranted.

Practical

PHQ-9 at each review. Do not abruptly stop the sertraline — review at 3-month thyroid check. If TSH is now normal and mood is not improving: maintain antidepressant. If TSH is normal and mood is significantly better: discuss tapering plan. Never stop sertraline abruptly.

Mood typically improves alongside TSH normalisation; sertraline review at 3 months is clinically appropriate

🤰

Preconception and Pregnancy Planning

Specialist/local pathway advice before conception; increase dose by 25–30% on positive test

Mechanism

Foetal thyroid function is not established until 16–20 weeks of gestation. Before this, the foetus is entirely dependent on maternal T4 for neurodevelopment. Even mild maternal hypothyroidism in the first trimester causes irreversible foetal neurological impairment.

Practical

This patient is trying to conceive: seek prompt specialist/local pathway advice (NG145 excludes pregnancy; RCOG GTG76, 2025) and optimise TSH before conception. When pregnancy test is positive: increase levothyroxine dose by 25–30% immediately (add 2 extra doses per week is a practical rule), arrange urgent TFTs. Refer promptly for joint obstetric–endocrine care — do not wait for the booking appointment.

Prompt dose increase and TSH within the trimester-specific range protect foetal neurodevelopment — the most important treatment target in this case

7D — Levothyroxine dosing guide

Levothyroxine dose is based on body weight (~1.6 mcg/kg/day ideal body weight) but NICE NG145 allows a full starting dose in younger, fit adults. NICE NG145: consider starting at 1.6 mcg/kg/day (rounded to the nearest 25 mcg) in adults under 65 with no cardiovascular disease; for adults 65 and over or with cardiovascular disease, start 25–50 mcg/day and titrate. A lower start (25–50 mcg) is for those 65 and over, with cardiovascular disease, severe longstanding hypothyroidism or possible adrenal insufficiency — full doses are dangerous in cardiac patients. Titrate in 25 mcg increments every 6–8 weeks, guided by TSH — never by symptoms alone.

Standard initiation (otherwise well adult <65)

Levothyroxine 1.6 mcg/kg/day OD — fasting, 30 min before breakfast

Start 1.6 mcg/kg/day (nearest 25 mcg; e.g. 100 mcg at 60 kg, 125 mcg at 80 kg) if under 65 with no cardiovascular disease (NICE NG145); recheck TSH + free T4 at 6–8 weeks
If TSH still elevated: increase by 25 mcg; recheck at 6–8 weeks
Continue in 25 mcg steps until TSH is within the reference range
Most adults require 75–150 mcg/day at maintenance
Target: TSH within the reference range — do not routinely increase the dose solely to reach a lower-half TSH (NICE NG145)

Never increase dose based on ongoing symptoms without rechecking TSH first — symptoms lag 6–8 weeks behind TSH normalisation.

Elderly or cardiac patient (>65 or significant IHD/arrhythmia)

Levothyroxine 25–50 mcg OD — cautious titration

Start 25–50 mcg OD; increase by 25 mcg, rechecking TSH from about 6 weeks after each change and about every 3 months until stable
ECG before initiation in significant cardiac disease
Too-rapid replacement precipitates angina, arrhythmia, or cardiac failure
Aim for a TSH within the reference range; titrate more slowly (or seek cardiology advice) if angina limits it
Cardiology input if significant IHD, LV impairment, or arrhythmia history

Slow titration is not undertreating — it is safe prescribing. Under-replacement symptoms must be balanced against cardiac risk of over-rapid treatment.

Pregnancy and trying to conceive

Levothyroxine — prompt specialist/local pathway advice; urgent titration

Use laboratory trimester-specific TSH ranges (or the local obstetric/endocrine protocol) — not fixed universal targets
New diagnosis: dose per specialist/local pathway advice; TSH and FT4 every 4–6 weeks until 20 weeks, then at 28 weeks; TSH within the trimester-specific reference range (RCOG GTG76, 2025)
When pregnancy confirmed: increase dose by 25–30% immediately (add 2 extra doses/week)
Joint obstetric–endocrine care; untreated or under-treated disease risks miscarriage and pre-eclampsia
Post-partum: reduce back to pre-pregnancy dose; recheck TSH at 6 weeks post-partum

Do not wait for specialist appointment before starting — foetal neurodevelopment risk is immediate. Refer to obstetric endocrinology simultaneously, not instead.

When TSH does not respond to levothyroxine — causes of apparent treatment failure

Poor adherence: Most common cause — missed doses; irregular timing; never changed behaviour from "as needed" mental model
Drug interaction (calcium, iron, PPI, cholestyramine): Reduces absorption by 20–40%; correct timing before escalating dose
Malabsorption: Coeliac disease (check anti-tTG), inflammatory bowel disease, or bowel resection — switch to liquid levothyroxine or soft-gel capsule formulation
Dose too low for body weight: Recalculate target dose (~1.6 mcg/kg ideal body weight)
Other causes of elevated TSH: Non-compliance, recent acute illness (TSH transiently rises), assay interference (biotin supplementation falsely lowers TSH in some assays)

Persistent symptoms despite TSH in target — what to do

Review TSH target: Aim within the reference range — do not routinely escalate solely to achieve a lower-half TSH (NICE NG145); assess adherence, absorption and other causes instead
Check free T4: Should be in mid-normal to upper-normal range; if low-normal TSH with low-normal T4, patient may be relatively under-replaced
Exclude other causes: Anaemia, coeliac disease, depression, fibromyalgia, sleep apnoea — all produce similar symptoms
T3/T4 combination: Controversial; NICE NG145 says do not routinely offer liothyronine (alone or with levothyroxine) for primary hypothyroidism, and BTA does not recommend it routinely; specialist decision only; has cardiac risk (T3 has shorter half-life, harder to titrate safely)
Endocrinology referral: If TSH consistently in range and symptoms persist after thorough primary care review

⚙ Interactive Medication Chooser — tick the patient profile, options re-tier live against NICE NG145 / SPC

A live, topic-scoped version of the standalone Medication Chooser. The static selector and reference cards below are unchanged.

7E — Medication options — guideline summary (no patient selection)

Situations this summary covers

Standard adult <65, no significant cardiac history
Elderly (>65) or significant cardiac disease — slow titration
Pregnant or trying to conceive — prompt specialist advice; trimester-specific range
Drug interaction (calcium, iron, PPI) — timing counselling critical
No response to levothyroxine — check adherence, interactions, malabsorption
Post-thyroidectomy / post-radioiodine — lifelong replacement
Amiodarone or lithium user — specialist coordination required
Symptoms persist despite TSH in range — exclude other causes first

Dosing approach

Standard adult (<65, no CVD): start 1.6 mcg/kg/day fasting; recheck TSH at 6–8 weeks; titrate in 25 mcg steps to a TSH within the reference range. Elderly/cardiac: start 25–50 mcg; slow titration. Pregnancy: prompt specialist advice; trimester-specific ranges; recheck about 4-weekly; increase dose 25–30% on positive pregnancy test. Interactions: calcium/iron/antacids about 4 hours apart. Never titrate by symptoms alone — always recheck TSH first.

Guideline summary — each situation is shown with what the guidance says for it, as written. Nothing is selected or worked out for an individual patient. Check doses in the SPC and your local formulary.

7F — Drug reference cards

Levothyroxine (T4)

Eltroxin; Euthyrox; Wockhardt; Accord; 25/50/75/100/125/150 mcg tablets

✓ First-line

First-line1.6 mcg/kg/day fasting if <65, no CVD (25–50 mcg if elderly/cardiac)

✓ Indications and considerations

Overt hypothyroidism (TSH >10 + low free T4) — treat all

Subclinical hypothyroidism: TSH >10 treat; TSH 4–10 individualise

Pregnancy: prompt specialist/local pathway advice; thresholds use trimester-specific ranges

Post-thyroidectomy / post-radioiodine — lifelong replacement

✗ Caution / monitoring required

Significant cardiac disease (IHD, arrhythmia, heart failure) — start 25 mcg; very slow titration; ECG before initiation

Untreated Addison's disease — replace cortisol first; levothyroxine can precipitate Addisonian crisis if adrenal reserve is low

Diabetes mellitus — levothyroxine can increase insulin or antidiabetic requirements (SPC); monitor glucose as dose titrates up

⚠ Signs of over-replacement (dose too high)

Palpitations, AF, tachycardia — suppress TSH below normal indicates over-replacement; risk of bone loss and cardiac arrhythmia

Insomnia, anxiety, tremor, heat intolerance — symptoms of iatrogenic hyperthyroidism

Suppressed TSH (<0.4 mU/L) — reduce dose; recheck in 6–8 weeks

🔬 Monitor

TSH (± free T4) from about 6 weeks after any dose change; about every 3 months until stable (NICE NG145); when stable: annually

4 weeks in pregnancy (not 6–8 weeks — more urgent titration needed)

After significant weight change or starting new interacting drug: recheck TSH

💬 Counselling phrase

"Take this tablet first thing in the morning on an empty stomach — before eating or drinking anything except water. Wait at least 30 minutes before breakfast. Your calcium tablet should be taken at least 4 hours later — lunchtime works perfectly. It's very important to be consistent about timing — taking it at different times each day makes it harder to know if the dose is right."

In SCA: the two most important levothyroxine counselling points are (1) fasting administration 30 min before food and (2) about 4-hour separation from calcium/iron/antacids. Both earn Tasks marks. Also: never titrate by symptoms alone — TSH must be rechecked at 6–8 weeks. For pregnancy: increase dose by 25–30% immediately on positive test.

Liothyronine (T3 — Specialist Only)

Morningside; 20 mcg tablets; short half-life (8–12 hours)

Specialist only

Specialist5–20 mcg OD–BD (very low starting dose)

✓ Use when (specialist-initiated only)

Persistent symptoms despite TSH consistently in target range on optimal levothyroxine — after all other causes excluded

Poor T4 to T3 conversion (deiodinase deficiency) — confirmed by specialist investigation

Never initiated in primary care — NICE NG145 says do not routinely offer liothyronine alone or in combination; BTA does not recommend it routinely

✗ Significant cautions

Cardiac arrhythmia risk — T3 has direct cardiac stimulant effect; very difficult to titrate safely; suppressed TSH with T3 worsens AF and bone loss risk

Not recommended in pregnancy — T3 crosses placenta less well than T4; levothyroxine (T4) is the preferred treatment in pregnancy

⚠ Key clinical points

Short half-life causes TSH fluctuation — harder to dose consistently than levothyroxine

Significantly more expensive than levothyroxine in the UK (cost implications for prescribing)

NICE NG145: do not routinely offer combination T3/T4 (insufficient evidence of benefit over levothyroxine alone; long-term harms uncertain); BTA agrees it is not routine

💬 Counselling phrase (if specialist has initiated)

"This is the active form of thyroid hormone — it works more quickly than the levothyroxine but also wears off more quickly. You'll take it twice a day. It's very important that your blood tests are checked regularly because getting the dose exactly right is more difficult with this medication."

In SCA: key knowledge points — T3 is NOT initiated in primary care; persistent symptoms on adequate T4 require other cause exclusion first; T3 has cardiac risk; NICE NG145 says do not routinely offer T3/T4 combination. Demonstrating this knowledge gains a Tasks mark.

Subclinical Hypothyroidism Management

Decision framework — not a drug; individualised approach

Individualise

Decision frameworkTSH 4–10 mU/L, normal free T4

✓ Treat subclinical hypothyroidism if

TSH ≥10 mU/L on 2 tests 3 months apart — consider levothyroxine (NICE NG145)

TSH above range but <10 with symptoms, age under 65 — consider a 6-month trial of levothyroxine (NICE NG145)

TSH 4–10 with positive TPO antibodies — higher risk of progression; closer monitoring, may favour a trial if symptomatic, but not by itself an indication

TSH 4–10 in pregnancy or trying to conceive — prompt specialist/local pathway advice; not automatic treatment

Confirmed on two separate samples ≥3 months apart before treatment (unless pregnancy)

⚠ Do not routinely treat if

TSH 4–10 and asymptomatic, or aged 65 or over — risk of over-treatment (AF, bone loss) may outweigh benefit

Single TSH reading only — must confirm on a second sample; TSH can transiently rise during illness or after acute stress

⚠ If treating subclinical hypothyroidism

Start levothyroxine exactly as in overt disease (by age and cardiac status); recheck TSH at 6–8 weeks; review the 6-month trial honestly

If TSH normalises and symptoms improve: confirm diagnosis and continue

If TSH normalises but symptoms do not improve: symptoms likely not thyroid-related — review diagnosis

If not treating: TSH annually if TPO-positive or other features of thyroid disease, otherwise every 2–3 years — to detect progression to overt

💬 Counselling phrase (subclinical, deciding to treat)

"Your thyroid is in what we call the 'borderline' range — the body is working harder than it should to maintain normal thyroid levels. Given your symptoms and the antibody result, I think it's worth trying a low-dose thyroid tablet to see if it helps. We'll review in 6 weeks and if you feel better and the blood test improves, we'll continue."

In SCA: the subclinical hypothyroidism decision framework is a key knowledge point. TSH ≥10 on 2 tests 3 months apart: consider levothyroxine (NICE NG145). TSH 4–10: individualise based on symptoms, TPO antibodies, age, pregnancy. Two samples before treating. If not treating, annual (TPO-positive) or 2–3-yearly monitoring. Demonstrating this nuance gains a Tasks mark.

Hashimoto's Thyroiditis — Specific Management

Autoimmune hypothyroidism; TPO antibodies positive; 70–80% of all hypothyroidism

Autoimmune cause

Most common causeLevothyroxine + monitoring

✓ Hashimoto's-specific considerations

Test for associated autoimmune conditions according to symptoms and risk (universal screening not required): type 1 diabetes (fasting glucose/HbA1c), coeliac disease (anti-tTG), Addison's disease (morning cortisol if clinically suspected), vitiligo, rheumatoid arthritis, pernicious anaemia (B12)

Thyroid fluctuation: Hashimoto's can cause transient hyperthyroidism ("Hashitoxicosis") before final hypothyroid state — warn patient that symptoms may vary initially

Family members: first-degree relatives have 5× increased risk; opportunistic TSH screening in symptomatic relatives

⚠ Avoid in Hashimoto's

High-dose iodine supplements (seaweed, kelp) — can worsen autoimmune inflammation (Wolff-Chaikoff effect)

Selenium supplementation in excess — may have a mild anti-TPO antibody effect at 200 mcg/day, but evidence is limited; do not recommend routinely unless deficient

🔬 Long-term monitoring

Annual TSH: Hashimoto's progresses at approximately 4%/year from subclinical to overt

Test for associated conditions if symptoms or risk features develop (e.g. GI symptoms, anaemia, variable levothyroxine needs)

Goitre monitoring: if present at diagnosis, annual palpation; refer for ultrasound if changes

💬 Counselling phrase

"The cause of your underactive thyroid is your immune system producing antibodies that gradually slow down the thyroid — this is very common, and it's not your fault or anything you did. It does mean it's a lifelong condition in most cases, but one that we can manage very effectively with the right tablet dose. It also means we should keep an eye on a few other autoimmune conditions that can sometimes occur alongside this one — we'll test for them if you develop symptoms that suggest one."

In SCA: identifying Hashimoto's means considering associated autoimmune conditions (coeliac, type 1 diabetes, B12 deficiency), testing according to symptoms and risk, and counselling about the autoimmune nature and the family risk. These are specific Tasks marks available in this scenario.

Myxoedema Coma — Emergency Protocol

Severe hypothyroidism emergency; IV levothyroxine; ITU management

Emergency

999 EmergencyIV T4 200–400 mcg loading; ITU

✓ Recognition — all of the following may be present

Hypothermia (<35°C) in context of known or suspected hypothyroidism

Confusion, reduced consciousness, or coma

Bradycardia and hypoventilation

Precipitants: cold exposure, infection, opioids/sedatives, stroke, surgery

🚨 GP action before 999 arrives

Call 999 immediately — do not delay for investigation

Passive rewarming (blankets — not active warming which causes vasodilatation and cardiovascular collapse)

ABCDE, ECG, glucose (hypoglycaemia common — treat if low) and temperature only if this does not delay transfer

Thyroid hormone and steroid treatment (coexisting adrenal insufficiency is common) follow the receiving hospital's protocol — do not delay transfer

⚠ Hospital management (ITU)

IV levothyroxine 200–400 mcg loading dose; then 50–100 mcg IV daily until oral route available

Assisted ventilation if hypoventilation; warming; electrolyte correction

Mortality 25–60% even with treatment — precipitant treatment essential

💬 Recognition in SCA context

Myxoedema coma is unlikely to be the SCA scenario itself but may appear in the stem as a case that "was initially treated as sepsis" or "presented with confusion." Recognising the combination of hypothermia + confusion + bradycardia in a patient with known hypothyroidism (or with classic signs) is the key knowledge point.

In SCA: myxoedema coma is an emergency — 999 is the answer, not "urgent referral to endocrine outpatients." The mortality rate (25–60%) and the precipitants (cold, infection, opioids) are specific knowledge points that gain Tasks marks.

Hypothyroidism in Pregnancy — Specific Protocol

Most critical management context; foetal neurodevelopment at risk

Urgent

Urgent initiationTrimester-specific TSH range

✓ Management principles

Overt hypothyroidism: start levothyroxine without waiting for the specialist appointment; newly detected subclinical disease — thresholds depend on TSH, FT4, TPO status and trimester-specific ranges (specialist advice)

On positive pregnancy test: increase existing levothyroxine dose by 25–30% immediately (add 2 doses/week)

TSH targets: laboratory trimester-specific ranges, or the local obstetric/endocrine protocol — not fixed universal targets

Recheck TSH every 4–6 weeks until 20 weeks, then at 28 weeks (RCOG GTG76, 2025); TSH within the trimester-specific reference range (aim for ≤2.5 mU/L pre-conception)

Post-partum: reduce to pre-pregnancy dose; recheck TSH at 6 weeks post-partum

⚠ Complications of untreated or inadequately treated hypothyroidism in pregnancy

Foetal intellectual disability and neurodevelopmental delay — irreversible; foetus depends on maternal T4 until 16–20 weeks

Increased miscarriage risk, pre-eclampsia, stillbirth, low birth weight

Post-partum thyroiditis: Hashimoto's patients at high risk of post-partum flare — check TSH at 3 and 6 months post-partum

🔬 Monitoring in pregnancy

TSH every 4–6 weeks until 20 weeks, then at 28 weeks (RCOG GTG76)

Refer promptly for joint obstetric–endocrine care — do not wait for booking

Post-partum thyroiditis screen at 3 and 6 months — TSH ± free T4

💬 Counselling phrase

"Before your baby can make its own thyroid hormone — which doesn't happen until 16 weeks — it completely relies on yours. Getting your thyroid levels right is one of the most important things we can do for your baby's brain development. We need to act on this quickly and keep checking your levels every month during the pregnancy."

In SCA: hypothyroidism in pregnancy is one of the highest-stakes clinical scenarios — the urgency (same-day action, not routine management) and the use of trimester-specific TSH ranges with prompt specialist advice are both examined knowledge points. Failing to recognise the urgency is a Tasks domain failure.

7G — Psychosocial impact of the diagnosis

🤝

Hypothyroidism affects identity, mood, relationships, and professional life — often before the diagnosis is made

The psychological impact of hypothyroidism extends beyond the biochemical. Patients with undiagnosed hypothyroidism often internalise their symptoms as personal failures — "I'm lazy," "I can't cope," "I'm gaining weight because of my diet." The diagnosis can bring relief but also grief (for the years of misattributed symptoms), frustration (at the delayed diagnosis), and anxiety about lifelong medication. The GP's role is to reframe the narrative and support the transition from "unwell without explanation" to "managed chronic condition."

💼

Work and Cognitive Function

Cognitive slowing, poor concentration, and memory difficulties from hypothyroidism significantly impair work performance — particularly in cognitively demanding roles. Teachers, managers, and professionals often experience a progressive decline in performance they attribute to "burning out."

A fit note is a legitimate and compassionate option for patients with severe symptomatic hypothyroidism during the titration period — particularly if the patient is a teacher managing 30 children while profoundly hypothyroid.

Framing the cognitive improvement as expected — "your thinking will improve as the levels come right" — provides hope and a concrete endpoint.

"A lot of the difficulty you've been having at work — the tiredness, difficulty concentrating — these are very likely to improve significantly as your thyroid levels come up to normal. It's the thyroid, not you."

⚖️

Weight and Body Image

Weight gain from hypothyroidism is frequently catastrophised by patients as "I've lost control" — and just as frequently dismissed by clinicians as "lifestyle." Reframing weight gain as a direct metabolic consequence of thyroid failure is one of the most important and restorative things a GP can do in this consultation.

However, honest expectation management is equally important: levothyroxine typically reduces hypothyroid-related weight by 2–5 kg. It does not produce dramatic weight loss if other factors are contributing.

Patients who expect complete weight normalisation and do not achieve it may lose faith in the treatment — and in themselves. Set a realistic, honest expectation.

"The weight gain you've experienced is a direct consequence of your thyroid slowing your metabolism down — it is not your fault. Most people lose 2–3 kg once the thyroid is treated, but I want to be honest that it's not a complete fix for weight."

😔

Depression and Misdiagnosis

In this case, the patient was started on an antidepressant without TFTs being checked — a common and consequential error in primary care. Addressing this sensitively without undermining the previous GP or causing the patient to lose confidence in primary care as a whole is a clinically challenging communication task.

Frame it as "a new finding that changes the picture" rather than "a mistake that was made." This is not dishonest — it is exactly what has happened: new information has become available.

The antidepressant (sertraline) should not be stopped abruptly. Plan a review at 3 months — if mood has improved with thyroid treatment, a supervised taper can be planned at that point.

"I want to be honest — I think your thyroid is the primary driver of your low mood. We should treat that first and then review whether the antidepressant is still needed at 3 months. We won't stop it suddenly."

💕

Relationships and Intimacy

Hypothyroid fatigue, low libido, and mood changes place significant strain on intimate relationships. Partners may interpret the patient's withdrawal, low energy, and emotional flattening as loss of interest or depression — creating relationship conflict on top of an undiagnosed illness.

After diagnosis, some patients and partners benefit from a simple explanation of what hypothyroidism does to energy, mood, and libido — and realistic reassurance that these changes are typically reversible with treatment.

Low libido from hypothyroidism should not be attributed to relationship problems without biochemical investigation. TSH should be one of the first tests in any patient presenting with new reduced libido or sexual dysfunction.

"Some of the changes you've noticed in your energy and mood — and in how you've been in your relationship — are very likely to improve as the thyroid treatment takes effect. It can take a few months, but the improvement is often quite marked."

🤰

Fertility and Preconception

In this case, the patient is trying to conceive. Untreated hypothyroidism causes anovulatory cycles, menorrhagia, and increased miscarriage risk. The TSH must be optimised before conception, with prompt specialist/local pathway advice — this is the most urgent priority in this consultation.

Framing this positively — "treating the thyroid significantly improves the chances of a successful pregnancy" — is honest and motivating. This is not a minor incidental finding; it is the single most clinically important aspect of the management plan for this patient.

Refer to obstetric endocrinology simultaneously with starting treatment — do not wait until pregnant to involve the specialist team.

"Treating your thyroid will significantly improve your chances of getting pregnant and having a healthy pregnancy. This is the most important thing we can do for you right now, and I want to act on it today."

💊

Lifelong Medication Anxiety

Many patients are anxious about committing to lifelong daily medication. Hashimoto's hypothyroidism is almost always permanent — this is a lifelong condition requiring lifelong treatment. Normalising this honestly ("it's similar to taking a blood pressure tablet or vitamin D — it becomes part of your daily routine") reduces anxiety.

Emphasising the simplicity of the regimen — one tablet daily, inexpensive, well-tolerated when dose is right — contrasts with the complexity of managing the undiagnosed condition (multiple GP visits, antidepressants, investigations for individual symptoms).

Address the fear of side effects directly: levothyroxine is bio-identical to the body's own T4 — when the dose is correct, there are essentially no side effects beyond the consequences of over-replacement (dose too high).

"This tablet is replacing something your body needs but isn't making enough of — it's bio-identical to your own hormone. When the dose is right, most people have no side effects at all. It becomes as simple as taking a vitamin every morning."

7H — Follow-up schedule

6–8 weeks — First dose response check

TSH + free T4. If TSH still above target: increase levothyroxine by 25 mcg; rebook in 6–8 weeks. If TSH in range: symptoms assessment — are they improving? If TSH low/suppressed: dose too high — reduce by 25 mcg; recheck. Review calcium interaction counselling. For this patient (TTC): check if pregnant — if so, increase dose by 25–30% immediately and refer to obstetric endocrinology urgently.

Action pointDose titration

3 months — Symptom and mood review

Review all hypothyroid symptoms: fatigue, weight, mood, constipation, hair loss, cold intolerance. PHQ-9 for mood. If TSH in range and mood improving: plan sertraline taper supervised. If TSH in range and mood not improving: primary depression likely coexisting — continue antidepressant; review diagnosis. Recheck TSH if dose changed at 6-week appointment.

Symptom reviewAntidepressant review

6 months — TSH stable confirmation

TSH + free T4. If stable and symptoms resolved: confirm maintenance dose; move to annual monitoring. Recheck cholesterol if elevated at diagnosis — typically normalises at 6 months once euthyroid. If symptoms persist despite TSH in range: screen for coeliac disease, B12, anaemia, sleep apnoea; review diagnosis; consider endocrinology referral if all excluded.

Stable confirmation

Annual — stable hypothyroidism review

Annual TSH ± free T4 (free T4 needed if TSH in range but symptoms). Dose review — requirements change with age, weight change (>10% change warrants dose recalculation), new medications (especially amiodarone, antiepileptics), menopause, and pregnancy. In Hashimoto's, ask about symptoms of associated autoimmune conditions and test if indicated (not routine annual screening). Hashimoto's: TPO antibodies do not need annual retesting — if positive at diagnosis, remains positive.

Annual review

Pregnancy — every 4–6 weeks to 20 weeks, then at 28 weeks

For this patient, once pregnant: TSH every 4–6 weeks until 20 weeks, then at 28 weeks (RCOG GTG76, 2025); TSH within the trimester-specific reference range. Increase the levothyroxine dose by about 25–30% as soon as pregnancy is confirmed: double the dose on 2 days each week, or increase by 25 micrograms/day if the pre-pregnancy dose is ≤100 micrograms/day, or 50 micrograms/day if >100 micrograms/day; arrange TFTs. Refer promptly for joint obstetric–endocrine care. Post-partum: reduce dose to pre-pregnancy level; recheck TSH at 6 weeks post-partum; check TSH at 3 and 6 months for post-partum thyroiditis (particularly in Hashimoto's).

Urgent pregnancy monitoring

7I — Monitoring: TSH targets and dose adjustment rules

Memory rule

Start 1.6 mcg/kg/day if <65 and no CVD (25–50 mcg elderly/cardiac); recheck TSH at 6–8 weeks; titrate in 25 mcg steps; target TSH within the reference range; never titrate by symptoms alone; separate from calcium/iron/antacids by about 4 hours. Pregnancy: TSH within the trimester-specific range; recheck every 4 weeks; increase dose 25–30% on positive test immediately. Annual TSH when stable.

Scenario	Test	Timing	Action threshold
Initial treatment	TSH + free T4	6–8 weeks after starting	TSH still elevated: increase 25 mcg. TSH in range: maintain; assess symptoms. TSH suppressed: reduce 25 mcg.
Any dose change	TSH + free T4	From about 6 weeks after change; about every 3 months until stable (NICE NG145)	Always recheck TSH — do not further adjust before the result is back. Patient perception of ongoing symptoms ≠ indication for dose increase before rechecking.
Stable hypothyroidism	TSH (± free T4)	Annually	TSH outside 0.4–4.0: adjust dose. TSH in range + new symptoms: check free T4 and exclude other causes. Weight change >10% or new drugs: recheck TSH.
Pregnancy	TSH + free T4	Every 4–6 weeks to 20 weeks, then at 28 weeks (RCOG GTG76)	TSH above the trimester-specific range: increase dose per the obstetric/endocrine plan. TSH suppressed: dose too high; reduce cautiously.
Subclinical hypothyroidism (not treating)	TSH + free T4	Annually if TPO-positive or thyroid disease features; otherwise 2–3-yearly	TSH >10 or new symptoms: consider treatment. TSH 4–10 stable: continue monitoring. Free T4 falling below range: treat.

Population	TSH target	Free T4 target
Standard adult (18–65)	Within the reference range (not routinely the lower half — NICE NG145)	Mid-to-upper normal range
Elderly >65 / cardiac disease	1.0–4.0 mU/L (accept higher TSH to avoid cardiac risk)	Lower-normal range acceptable
Pregnancy — 1st trimester	Laboratory trimester-specific range (or local protocol)	Normal range; upper normal preferred
Pregnancy — 2nd/3rd trimester	Laboratory trimester-specific range (or local protocol)	Normal range
Thyroid cancer (post-thyroidectomy)	Set by the thyroid cancer team (specialist surveillance protocol)	Per specialist plan
Subclinical hypothyroidism not treated	Annual monitoring; treat if TSH >10 or progresses	Normal

7J — Safety-netting: exact phrases + medico-legal rationale

⚠ Three scenario-specific safety-net phrases

Why safety-netting matters beyond clinical care

Calcium/levothyroxine interaction counselling documented — if TSH does not normalise at 6 weeks, the interaction was addressed; dose escalation without this counselling first is premature

Pregnancy safety-net documented — if foetal thyroid complication occurs, documented counselling of immediate dose increase on positive test is essential medico-legal protection

Myxoedema safety-net — patients with chronic hypothyroidism risk acute decompensation; documented awareness of emergency features is part of safe management

Do not titrate by symptoms alone — this must be documented in every levothyroxine management note; TSH must be rechecked before dose change

Annual TSH monitoring documented — hypothyroidism is a lifelong condition requiring annual biochemical review; missing annual monitoring creates medico-legal risk if complications develop

In SCA: safety-netting must include the specific calcium interaction and the pregnancy protocol — both are examined clinical knowledge points with specific Tasks domain marks available

6–8 weeksTSH + free T4 review; dose titration decision; calcium interaction compliance check; pregnancy status if TTC

Positive pregnancy testSame-day call; increase dose 25–30% immediately; TSH recheck in 4 weeks; obstetric endocrinology referral

3 months / AnnuallyMood review (sertraline at 3 months); cholesterol recheck at 6 months; annual TSH when stable

🎓 SCA Checkpoint — Step 7 (Final)TasksRelating to OthersGlobal Skills

Closing the consultation

"So to summarise: your thyroid is underactive and I'm prescribing levothyroxine at a full replacement dose worked out from your weight — about 100 to 125 micrograms — which you take first thing in the morning on an empty stomach. Your calcium tablet must be at least 4 hours apart — lunchtime works well. I'm booking your blood test in 6 weeks."

"Because you're trying to conceive — the moment you get a positive pregnancy test, please call us the same day. We will increase your dose immediately and arrange an urgent blood test. Don't wait for a routine appointment."

"I'll also review the sertraline at your 3-month appointment — once your thyroid levels are right, your mood will very likely improve, and we can then decide whether you still need it."

"Is there anything else on your mind before we finish?"

Deductions — closing

Calcium interaction not counselled — the most important practical instruction in this consultation
Pregnancy protocol not given — for a patient TTC, this is a critical safety-net omission
Sertraline stopped immediately or abruptly — never abrupt cessation; review planned
Starting a full weight-based dose in an elderly or cardiac patient without a slow titration plan
Promising complete weight and mood resolution — overpromising damages therapeutic trust
Closing question absent

Tasks domain — full closing criteria

TSH + free T4 + TPO antibodies ordered
Levothyroxine 1.6 mcg/kg/day (under 65, no CVD) prescribed with correct timing instruction (fasting, 30 min before food)
Calcium interaction counselled — minimum 4 hours apart
Pregnancy protocol given — call same day; dose increase immediately
Sertraline reviewed with clear plan (not stopped; review at 3 months)
6–8 week follow-up TSH booked before patient leaves
Myxoedema safety-net for emergency features

Relating to Others — full closing criteria

Thermostat analogy used — all symptoms linked to one cause
Antidepressant addressed sensitively — "new finding changes the picture," not "previous GP made an error"
Weight expectations managed honestly — partial improvement, not complete resolution
Fertility urgency communicated without causing panic
Lifelong medication concern addressed — reframed as simple daily habit
Understanding checked; closing question asked

🔴 Red

Calcium interaction not counselled. Pregnancy protocol absent. Sertraline stopped abruptly or not reviewed. TSH follow-up not booked. Closing question absent.

🟠 Amber

Levothyroxine prescribed but calcium interaction not specifically timed. Pregnancy protocol mentioned but not specific enough ("increase your dose" without "same day, immediately on positive test"). Antidepressant not addressed.

🟢 Green

Calcium interaction specifically counselled (4 hours, lunchtime example). Pregnancy protocol explicit (call same day, immediate dose increase). Sertraline reviewed with 3-month plan. Thermostat analogy. Closing question.

"I've been feeling absolutely exhausted for the past few months — gaining weight, freezing cold all the time, my hair's been falling out. I was started on an antidepressant a few weeks ago but I'm not sure it's the right thing."

Who you are

Sarah Brennan, 42 years old, secondary school teacher. 4-month history of progressive fatigue (sleeping 9–10 hours, still exhausted), 5 kg weight gain with no dietary change, feeling cold even in a warm classroom, constipation (every 3–4 days), hair thinning (particularly the front hairline and eyebrows), dry skin, low mood and difficulty concentrating. Started sertraline 50 mg 3 weeks ago by a locum GP who did not check TFTs. Takes calcium carbonate 500 mg daily for osteoporosis prevention advice from a sports physio. No cardiac history. Not pregnant but actively trying to conceive with her partner for 6 months. No family history of thyroid disease that she knows of. Non-smoker. BMI 27.

Hidden agenda

Two main concerns: (1) She is trying to conceive and has been told by her partner that "the antidepressant might affect fertility." She is worried but has not been told why the antidepressant was started or what to expect. She will not volunteer this unless specifically asked about pregnancy or fertility plans. If the GP asks and she discloses — and then receives a clear, urgent, and reassuring response ("we will sort this quickly and it significantly improves your fertility") — she becomes visibly relieved and fully engaged. (2) She suspects she has a thyroid problem because she Googled her symptoms at 2am. She is frustrated that it wasn't checked. She will not volunteer this unless asked "what do you think might be causing this?" — at which point she will say "I thought it might be my thyroid but the last GP didn't seem to think so."

Symptoms if asked directly

Fatigue: constant, not relieved by sleep, present even on weekends when not working
Weight: 5 kg gained over 4 months without diet change
Cold intolerance: wears extra layers; feels cold when colleagues are comfortable
Hair: noticeably thinner; partner has commented on it; outer third of eyebrows sparse
Bowels: every 3–4 days, harder than usual
Mood: flat, not quite depressed — "more like switched off"
Voice: slightly huskier than before — first noticed it 2 months ago
Periods: heavier than before, lasting 6–7 days (was 4)
No palpitations, no heat intolerance, no sweating, no tremor

Bonus details

If asked about calcium carbonate: "I take it with breakfast — does that matter?"
If asked about family history: "Actually, now you mention it — my older sister has something wrong with her thyroid. She takes a tablet for it."
Challenge: "The locum told me I was depressed — was she wrong? Should I stop the antidepressant?"

"Am I going to be on tablets forever? And will treating my thyroid actually help me get pregnant? I'm really worried about that."

Resolution criteria: Sarah will accept the plan if the candidate (1) confirms the suspected thyroid diagnosis with a clear explanation using the thermostat analogy; (2) specifically addresses the calcium timing — "take levothyroxine before breakfast, calcium at lunchtime, minimum 4 hours apart"; (3) addresses fertility explicitly and urgently — "we need to get your thyroid levels right before you conceive, and once pregnant, call us immediately to increase your dose"; (4) handles the antidepressant sensitively — "review at 3 months, not stopping now"; (5) books a 6–8 week blood test; (6) asks the closing question.

🏥

Clinic Quick Reference

Hypothyroidism — Clinical Decision Framework

NICE NG145

▼expand

🚦 1 — Triage

Elevated TSH or symptomatic hypothyroidism → assess urgency and context

↓

🔴 Emergency / Urgent

Myxoedema coma: hypothermia + confusion + bradycardia → 999
Pregnancy / TTC: raised TSH → prompt specialist/local pathway advice (trimester-specific ranges); overt → start levothyroxine
Rapidly enlarging goitre → suspected thyroid cancer pathway referral
Severe cardiac complications before starting → cardiology first

999 / Same-day urgent action

🟠 Specialist coordination

Amiodarone-induced: never stop amiodarone; treat with levothyroxine alongside
Elderly / cardiac: 25 mcg start; ECG; cardiology input
Persistent symptoms on optimal T4 → endocrine referral

Specialist coordination

🟢 Routine Primary Care

Overt hypothyroidism: start 1.6 mcg/kg/day if <65, no CVD (25–50 mcg if older/cardiac); TSH at 6–8 weeks
Subclinical TSH ≥10 on 2 tests 3 months apart: consider levothyroxine (NICE NG145)
Subclinical TSH 4–10: individualise (symptoms, TPO, age, pregnancy)
Annual TSH when stable

GP management

📊 2 — Key Numbers

1.6 mcg/kg

Starting dose if <65, no CVD (25–50 mcg elderly/cardiac)

6–8 weeks

TSH recheck interval after any dose change

Ref. range

TSH target — within the reference range (not routinely lower half)

TSH >10

Subclinical: consider levothyroxine if TSH ≥10 twice, 3 months apart (NICE NG145)

TSH 4–10

Subclinical — individualise: symptoms, TPO antibodies, age, pregnancy

Trimester

Pregnancy — laboratory trimester-specific TSH range; prompt specialist advice

30 min

Take levothyroxine fasting 30 min before breakfast

4 hours

Separation from calcium, iron, antacids

25 mcg

Titration step increment; also increment for pregnancy (add 2 doses/week)

4 weeks

TSH recheck interval in pregnancy (not 6–8 weeks)

Annual TSH

Monitoring interval when stable on levothyroxine

Never T3 in 1°

Liothyronine (T3) — specialist-initiated only; not in primary care

💊 3 — Levothyroxine Dosing Quick Reference

Initiation and Titration

Standard (<65, no CVD): 1.6 mcg/kg/day fasting → TSH at 6–8 weeks → titrate ↑25 mcg until TSH within reference range

Elderly/cardiac: 25–50 mcg OD → cautious titration; ECG if cardiac disease; TSH within reference range

Pregnancy: prompt specialist advice; trimester-specific TSH range; recheck about every 4 weeks; ↑25–30% on positive test

Never: titrate by symptoms alone; always wait for 6-week TSH before changing dose

⚠ Calcium, iron and antacids reduce absorption — separate by about 4 hours; PPIs vary — keep consistent and recheck after changes

TSH Not Responding — Check First

1. Adherence — missed doses, irregular timing

2. Drug interaction — calcium/iron/PPI taken with levothyroxine

3. Malabsorption — coeliac disease (check anti-tTG)

4. Dose too low for weight — recalculate (~1.6 mcg/kg IBW)

5. Biotin supplementation — can falsely alter TSH assay

Then: consider endocrine referral if all excluded

⚠ 4 — Safety Netting and Follow-Up

Follow-up timeline

6–8 weeks: TSH + free T4; dose titration; pregnancy check if TTC

3 months: Symptom + mood review; antidepressant review

6 months: TSH stable confirmation; recheck cholesterol

Annual: TSH; dose review; autoimmune testing if symptoms (Hashimoto's)

Pregnancy (if confirmed): TSH every 4 weeks; obstetric endocrine referral

🔬 5 — Monitoring

Scenario	Test	Timing	Action threshold
Any dose change	TSH + free T4	6–8 weeks	TSH elevated: increase 25 mcg. TSH suppressed: reduce 25 mcg. Never change dose before 6-week result.
Stable hypothyroidism	TSH (± free T4)	Annually	TSH outside 0.4–4.0: adjust dose. Weight change >10% or new interacting drug: recheck TSH.
Pregnancy	TSH + free T4	Every 4 weeks (first 20 weeks)	TSH above trimester-specific range: increase dose. Post-partum: reduce to pre-pregnancy dose; recheck at 6 weeks.
Subclinical, not treating	TSH + free T4	Annually if TPO+; otherwise 2–3-yearly	TSH >10: treat. TSH 4–10 progressing: consider treatment.

🚨 Emergency: Myxoedema coma (hypothermia + confusion + bradycardia = 999). Untreated hypothyroidism in pregnancy (same-day action + obstetric referral). Rapidly enlarging goitre (suspected cancer pathway).

💊 Critical interaction: Calcium, iron and antacids reduce levothyroxine absorption. Separate by about 4 hours (PPIs have variable effects — keep consistent). Most common cause of apparent levothyroxine treatment failure in primary care.

🎓

SCA Exam Quick Reference

SCA Consultation Blueprint

Tasks · Relating to Others · Global Skills · RAG guide

▼expand

🕐 12-Minute Flow

0–2 min

Reference Stem + Open

"Before we discuss the antidepressant, I'd like to check your thyroid — based on what you're describing, I think that may be the cause. Tell me more about how you've been feeling."

GSRO

✗ Not referencing existing diagnosis/medication in stem

2–6 min

Pregnancy + Drug History + ICE

"Are you pregnant or trying to conceive? What medications are you on — calcium? Do you take anything with breakfast? Is there something you've suspected might be causing this?"

TasksRO

✗ Not asking about pregnancy · ✗ Calcium interaction missed

6–7 min

Examination

"I'd like to feel your thyroid gland and check your heart rate and reflexes — the reflexes give us a clue about how your thyroid is affecting your body."

Tasks

✗ No thyroid examination · ✗ No cardiovascular assessment

7–10 min

Diagnosis + Antidepressant + Plan

"Your thyroid is like the body's thermostat — when it's underactive, everything slows down. This explains all your symptoms. Levothyroxine — before breakfast, calcium at lunchtime, 4 hours apart."

TasksRO

✗ Antidepressant stopped abruptly · ✗ Calcium interaction not timed

10–12 min

Pregnancy Protocol + Follow-Up + Close

"Positive pregnancy test = call us same day; we increase your dose immediately. 6-week blood test booked. Is there anything else?"

TasksRO

✗ Pregnancy protocol absent · ✗ No follow-up booked · ✗ No closing question

🔴🟠🟢 RAG Scoring

Tasks

🟢

Pregnancy asked; calcium 4-hour timing given; weight-based dose prescribed fasting; 6-week TSH booked; pregnancy protocol explicit; antidepressant review planned; myxoedema safety-net

🟠

Pregnancy asked but protocol not explicit; calcium mentioned but not timed specifically; antidepressant not reviewed

🔴

Pregnancy not asked; calcium interaction missed; sertraline stopped abruptly; no TSH follow-up; T3 initiated in primary care

Relating to Others

🟢

Thermostat analogy; weight reframed as metabolic; antidepressant handled sensitively; timeline 3–6 months; lifelong medication normalised; understanding checked; closing question

🟠

ICE partially explored; weight expectations not managed; antidepressant not addressed; timeline not set

🔴

ICE absent; weight attributed to lifestyle; antidepressant abruptly stopped; promises complete weight loss; no closing question

💬 Key Phrases

Stem reference

"Before we talk about the antidepressant, I'd like to check your thyroid — based on what you're describing, I think that may be what's driving this."

Thermostat analogy

"Your thyroid is like the body's thermostat — when it's underactive, everything slows down: energy, metabolism, mood, bowels, temperature control."

Weight reframe

"The weight gain is a direct metabolic consequence of the thyroid slowing down — it is not your fault."

Calcium interaction

"Levothyroxine before breakfast on an empty stomach; your calcium at lunchtime — at least 4 hours apart. Together, the calcium blocks the tablet."

Pregnancy protocol

"The moment you get a positive pregnancy test — call us same day. We increase your dose immediately. Don't wait for a routine appointment."

Antidepressant plan

"Don't stop the sertraline suddenly — let's review it at 3 months once your thyroid levels are right. Your mood will very likely improve."

🚫 9 Danger Zones

✗

Not asking about pregnancy / fertility
→ Most urgency-changing question in any woman of childbearing age with new hypothyroidism

✗

Calcium interaction not counselled
→ Most common cause of levothyroxine treatment failure; must be timed specifically (4 hours)

✗

Sertraline stopped abruptly
→ Never abrupt cessation; plan review at 3 months when TSH normalises

✗

Full weight-based dose in elderly/cardiac
→ Start 25–50 mcg; very slow titration; cardiology input; too-rapid replacement precipitates arrhythmia

✗

Titrating dose by symptoms not TSH
→ Symptoms lag 6–8 weeks behind biochemical response; always recheck TSH before changing dose

✗

T3 (liothyronine) initiated in primary care
→ Specialist-initiated only; NICE NG145: do not routinely offer; BTA: not routine; cardiac risk

✗

Promising complete weight loss
→ Typically 2–5 kg metabolic component; honest expectation prevents loss of therapeutic trust

✗

Pregnancy protocol absent
→ Must be explicit: "call same day on positive test; increase dose immediately"

✗

Closing question not asked
→ "Is there anything else?" is a consistently marked RO domain item

💊 Drug Quick-Pick

Overt hypothyroidism, standard adult

→

Levothyroxine 1.6 mcg/kg/day fasting

Start here

Elderly / significant cardiac disease

→

Levothyroxine 25 mcg OD slow tit.

ECG first

Pregnancy / TTC — raised TSH

→

Specialist advice; trimester-specific range

Same-day

On pregnancy, positive test

→

Increase dose 25–30% immediately

Same day

Persistent symptoms, TSH in range

→

Exclude other causes first

Then endocrine

T3 / combination therapy requested

→

Endocrinology only — not primary care

Cardiac risk

⛔ Never titrate by symptoms alone — always wait for 6-week TSH · Never T3 in primary care · about 4-hour separation from calcium/iron/antacids · Pregnancy = same-day action

Hypothyroidism · GP Clinical Reasoning Framework v2 · NICE NG145 · British Thyroid Association Executive Committee statement on management of primary hypothyroidism (Clin Endocrinol 2016) · European Thyroid Association Guidelines on Hypothyroidism (international)

v3: Dual tailored summaries · Pregnancy protocol as highest-priority safety-net · Calcium interaction as primary counselling point · Antidepressant management integrated · Myxoedema emergency recognition · Subclinical hypothyroidism decision framework

Teaching clinicians why each step matters — not just what to do · Check doses in the SPC and your local formulary · Clinical judgement takes precedence

Hypothyroidism

Red Flags

999 or Same-Day Specialist

Endocrine Referral

Primary Care Management

Hashimoto's thyroiditis (autoimmune)

Post-thyroidectomy or post-radioiodine

Iodine deficiency (rare in UK)

Amiodarone-induced hypothyroidism

Lithium-induced hypothyroidism

Subclinical hypothyroidism (TSH 4–10)

Myxoedema coma

Hypothyroidism in pregnancy

Validate — name their expectation

Explain — share your clinical reasoning

Negotiate — offer something concrete today

Work and Cognitive Function

Weight and Body Image

Depression and Misdiagnosis

Relationships and Intimacy

Fertility and Preconception

Lifelong Medication Anxiety

6–8 weeks — First dose response check

3 months — Symptom and mood review

6 months — TSH stable confirmation

Annual — stable hypothyroidism review

Pregnancy — every 4–6 weeks to 20 weeks, then at 28 weeks

Memory rule

⚠ Three scenario-specific safety-net phrases

Why safety-netting matters beyond clinical care

🎭 Patient actor brief — click to practise

Who you are

Hidden agenda

Symptoms if asked directly

Bonus details