Amenorrhoea Algorithm

Safety

Red Flags & Urgent Exclusions — Act First

Done

Screen for dangerous or time-sensitive diagnoses before any further history. If any red flag is present, act immediately — do not defer.

Pregnancy Exclude at the outset in anyone with a uterus where pregnancy is possible, regardless of contraception → urine βhCG today; serum βhCG if negative but suspicion high, or pain/bleeding. Positive test with pain, bleeding, syncope or instability → immediate EPU / ED

Ectopic pregnancy Lower abdominal pain + shoulder-tip pain + haemodynamic instability → 999 immediately

Pituitary apoplexy Sudden severe headache + visual field defect + bitemporal hemianopia → 999 — haemorrhage into pituitary tumour

Adrenal crisis Collapse, hypotension, vomiting, pigmentation, preceding weight loss → 999 — Addison's / adrenal insufficiency

Eating disorder / malnutrition BMI <17.5 or rapid weight loss + lanugo / bradycardia / electrolyte disturbance → same-day assessment; cardiac arrhythmia risk

Turner syndrome (delayed) Primary amenorrhoea + short stature, absent secondary sexual characteristics, dysmorphic features or suggestive family history → paediatric/adolescent gynaecology or endocrine referral; specialist arranges karyotype, cardiac imaging (CoA risk) and renal evaluation

Androgen-secreting tumour Rapid virilisation, clitoromegaly, deepening voice, rapidly progressive hirsutism or markedly elevated androgens (interpret testosterone against the local assay range) → Urgent gynaecology / endocrinology assessment

Prolactinoma / pituitary mass Galactorrhoea + visual field loss + headache → same-day endocrine assessment; specialist-directed MRI pituitary. Sudden severe headache or acute neurology → emergency

Asherman's syndrome History of uterine curettage / ERPC + cyclical pelvic pain but no bleeding → gynaecology referral for pelvic imaging/hysteroscopic assessment; expedite if severe cyclical pain, haematometra, infection or another acute pelvic process

Premature ovarian insufficiency <40 Menopausal symptoms / no or infrequent periods + raised FSH on two samples 4–6 weeks apart (NICE NG23; not a single FSH, not AMH) → HRT/CHC counselling, bone, cardiovascular, psychological and fertility assessment; specialist input where indicated

Exclude pregnancy early in anyone with a uterus where pregnancy is possible — including those who believe they cannot conceive or report using contraception. Ectopic pregnancy rupture carries significant maternal mortality risk and presents deceptively.

Pituitary apoplexy is rare but life-threatening; untreated it causes permanent hypopituitarism and blindness. Bitemporal hemianopia reflects compression of the optic chiasm.

Eating disorders: Hypokalaemia from purging causes fatal arrhythmias; refeeding syndrome is an inpatient emergency. RCPsych MEED guidance (Medical Emergencies in Eating Disorders, 2022, which replaced MARSIPAN) mandates urgent physical assessment for high-risk patients.

Androgen-secreting tumours (ovarian/adrenal) are rare but aggressive — rapid virilisation or markedly elevated androgens should never be attributed to PCOS without specialist assessment. Interpret testosterone against the local assay range; a mild or moderate elevation in longstanding PCOS is not, by itself, an emergency.

Diagnose

Confirm Type — Primary vs Secondary Amenorrhoea

Done

Establish the type first — this determines the entire diagnostic pathway. Use a structured menstrual and general history.

Definition

Primary: Investigate if no menarche by age 15, or more than 3 years after breast development began. Assess earlier if no breast development by age 13, abnormal genital development, cyclic pelvic pain, virilisation or other concerning features — do not wait until 16 consensus definition
Secondary: Cessation of previously regular menses for ≥3 months, or irregular menses absent for ≥6 months

Key history

Age of onset · Last menstrual period · Cycle history · Contraception use · Pregnancy/breastfeeding · Menopausal symptoms (flushes, night sweats) · Weight change · Exercise level and energy availability · Eating disorder screen · Stress · Hyperandrogenism · Cyclical pelvic pain · Systemic illness · Medications (antipsychotics, opioids, metoclopramide, combined pill)

Red flag Qs

Galactorrhoea? · Headaches / visual changes? · Recent uterine procedure? · Pelvic pain cyclically (Asherman's)? · Family history of early menopause or Turner's?

Pregnancy test

Exclude pregnancy at the outset in anyone with a uterus where pregnancy is possible, regardless of reported contraception — urine βhCG; serum βhCG if urine negative but suspicion high, or pain/bleeding with possible ectopic. Document result in notes Good practice

Menstrual diary

Ask patient to complete 3-month diary if ongoing monitoring needed — record any breakthrough bleed, spotting, discharge, or cyclical pain

Drug history

Antipsychotics (risperidone, haloperidol) · Opioids · Metoclopramide · Domperidone · Methyldopa · Verapamil — all elevate prolactin; stop if clinically appropriate

Primary and secondary amenorrhoea have overlapping but distinct differentials. Primary is more likely to involve structural/genetic causes (Turner's, Müllerian agenesis, imperforate hymen), while secondary is more commonly functional (hypothalamic, PCOS, thyroid, prolactinoma).

Drug-induced hyperprolactinaemia is frequently missed and resolves on stopping the causative agent. Always review the drug chart before requesting imaging.

Diagnose

Classification — Identify the Underlying Cause

Done

Classify by anatomical level using the WHO framework. Each category has distinct bloods, features, and management.

WHO I — Hypothalamic

Hypogonadotrophic hypogonadism: Low FSH/LH, low oestrogen. Causes: extreme exercise RED-S, low BMI, stress, eating disorder, Kallmann's syndrome (anosmia). Hallmark: low/normal FSH with low oestradiol

WHO II — Pituitary

Normogonadotrophic (normo-oestrogenic) anovulation — mostly PCOS: Normal FSH; an LH:FSH ratio is not diagnostic of PCOS. Elevated prolactin → prolactinoma. Includes Sheehan's syndrome (post-partum pituitary infarct)

WHO III — Ovarian

Hypergonadotrophic hypogonadism: High FSH (raised on 2 samples 4–6 weeks apart — NICE NG23; do not diagnose POI on a single FSH or on AMH) + low oestrogen. Causes: Premature Ovarian Insufficiency (POI), Turner syndrome, chemotherapy, autoimmune oophoritis

Outflow tract

Structural: Imperforate hymen (cyclical pain, haematocolpos), Müllerian agenesis (MRKH), Asherman's syndrome (post-curettage intrauterine adhesions), cervical stenosis. Primary amenorrhoea: also 46,XY differences of sex development and gonadal dysgenesis

Systemic

Thyroid disease (hypo- or hyperthyroidism) · Hyperprolactinaemia (any cause) · Cushing's syndrome · Chronic illness (IBD, CKD, coeliac) · Functional amenorrhoea of any cause

PCOS (most common)

Requires 2 of 3 Rotterdam criteria: ovulatory dysfunction + clinical/biochemical hyperandrogenism + polycystic ovarian morphology, after excluding pregnancy, thyroid disease, hyperprolactinaemia, non-classic CAH and androgen-secreting tumours where indicated. Ultrasound is not required if ovulatory dysfunction and hyperandrogenism are both present. LH:FSH ratio is not a criterion; do not use AMH as a substitute for clinical assessment. In adolescents, adult Rotterdam criteria should not be applied without modification Intl PCOS guideline 2023 (international)

The WHO classification directly drives investigation and management. WHO I (hypothalamic) needs caloric rehabilitation and stress reduction; WHO III (POI) needs HRT or CHC for bone and cardiovascular protection — these are fundamentally different treatment goals.

PCOS is a common cause of secondary amenorrhoea but other causes must be excluded — thyroid disease, hyperprolactinaemia, and non-classical congenital adrenal hyperplasia must be ruled out first (International PCOS guideline 2023, international).

RED-S (Relative Energy Deficiency in Sport) is under-recognised in athletes and dancers — it represents a spectrum from subclinical to life-threatening and requires multidisciplinary input.

Diagnose

Targeted Clinical Examination

Done

A focused examination is essential — findings guide investigation and can reveal the diagnosis immediately. Obtain informed consent; chaperone for all intimate examination.

General / nutritional

BMI (calculate — not just weight) · Lanugo hair · Muscle wasting · Cachexia · Signs of chronic illness. Low BMI or rapid weight loss should prompt eating-disorder assessment (BMI alone is not diagnostic)

Thyroid

Goitre · Tremor · Bradycardia or tachycardia · Dry skin / hair loss · Exophthalmos. Thyroid disease commonly causes menstrual disruption

Hyperandrogen signs

Ferriman-Gallwey score for hirsutism (modified score ≥4–6, depending on ethnicity = hirsutism) · Acne distribution · Clitoromegaly · Male-pattern baldness. Severe rapid virilisation → ? tumour

Galactorrhoea

Gentle bilateral breast expression — milky discharge = hyperprolactinaemia until proven otherwise. Document uni vs bilateral

Visual fields

Confrontation visual fields both eyes — bitemporal hemianopia indicates optic chiasm compression from pituitary mass → same-day endocrine/emergency assessment (specialist-directed MRI)

Turner stigmata

Short stature · Webbed neck · Shield chest · Wide-carrying angle (cubitus valgus) · Low posterior hairline · Primary amenorrhoea → paediatric/adolescent gynaecology or endocrine referral (specialist karyotype, cardiac and renal evaluation)

Pelvic / genital

External: imperforate hymen (bluish bulge), ambiguous genitalia. Internal (if indicated): uterus presence (MRKH), tenderness (Asherman's). Consider referring for USS rather than clinical exam in primary amenorrhoea

Skin / adrenal

Striae (Cushing's) · Central obesity · Hyperpigmentation (Addison's) · Acanthosis nigricans (insulin resistance in PCOS)

Examination findings can make or change the diagnosis immediately, avoiding unnecessary investigations. A woman with galactorrhoea + bitemporal hemianopia has a pituitary macroadenoma until proven otherwise — this is a same-day referral.

The Ferriman-Gallwey score is the validated clinical tool for hirsutism and should be documented for monitoring response to treatment. A modified score of ≥4–6, depending on ethnicity, indicates hirsutism (International PCOS guideline 2023).

Acanthosis nigricans in PCOS signals insulin resistance and should prompt fasting glucose / HbA1c — this patient is at high risk of type 2 diabetes and requires metabolic management, not just cycle regulation.

Diagnose

Investigations — Stepwise Approach

Done

After excluding pregnancy, order investigations in tiers — targeted first-line bloods answer most cases. Second-line only if first-line unclear or abnormal, or by phenotype. Do not routinely order oestradiol, testosterone, fasting lipids and extensive endocrine tests for every presentation.

FIRST LINE — All

βhCG urine (if not already done) · FSH + LH (day 2–5 if any cycle) · Prolactin (rested sample — fasting not needed; repeat if elevated) · TSH (± free T4 if indicated) · Oestradiol if hypogonadism suspected · Total testosterone + SHBG (free androgen index) if hyperandrogenism/PCOS suspected · HbA1c or glucose according to metabolic risk · haematinics or coeliac serology by phenotype

FIRST LINE — Add if PCOS suspected

Glycaemic assessment and lipids according to baseline risk · Pelvic USS only if needed for diagnosis — not required when ovulatory dysfunction and hyperandrogenism are both present (transvaginal preferred; transabdominal if never sexually active) — ovarian volume >10 mL, ≥20 follicles per ovary 2–9 mm = polycystic morphology Intl PCOS guideline 2023

FIRST LINE — Add if POI suspected

Raised FSH on two samples 4–6 weeks apart (NICE NG23; ESHRE 2024, international, uses a single FSH >25 IU/L with ≥4 months of disordered cycles) · do not diagnose on a single FSH; do not routinely use AMH to diagnose POI · genetic (karyotype) and autoimmune evaluation (e.g. anti-TPO) usually specialist-guided · DXA according to baseline fracture risk and local menopause/POI guidance

SECOND LINE — Elevated prolactin

Repeat a mild or unexpected elevation using a rested sample · review pregnancy, medicines, hypothyroidism, renal disease and macroprolactin · Refer for endocrine advice and imaging (MRI pituitary) if persistent and unexplained, symptoms suggest pituitary disease, prolactin is markedly elevated, or visual/neurological symptoms — not solely because a fixed threshold is exceeded

SECOND LINE — Androgens high

Only where clinically indicated: 17-OHP (morning) where non-classic CAH is possible — abnormal result → endocrine assessment · DHEAS (adrenal androgen) · 24h urinary cortisol or overnight dexamethasone suppression test if Cushing's suspected

SECOND LINE — Structural

Pelvic USS (primary amenorrhoea — confirm uterus/ovary presence; alongside specialist referral) · MRI pelvis if MRKH/outflow abnormality suspected · Hysteroscopy (secondary care) if Asherman's suspected post-curettage

NOT routinely needed

ACTH levels · Inhibin B · Progesterone challenge test (outdated) · 21-day progesterone unless ovulation tracking needed · FSH/LH single sample without context

Interpretation tips

High FSH + low oestradiol = ovarian failure (POI / menopause)
Low FSH + low oestradiol = hypothalamic/pituitary failure
Normal FSH + clinical/biochemical hyperandrogenism ± ovulatory dysfunction = consider PCOS (LH:FSH ratio not diagnostic)
High prolactin = repeat rested sample; if persistent and unexplained → endocrine advice ± imaging
Markedly elevated testosterone (vs local assay range) or rapid virilisation = urgent specialist assessment

FSH + LH distinguish the level of the problem — persistently high gonadotrophins mean the ovary has failed and the pituitary is trying harder; low gonadotrophins mean the hypothalamus or pituitary has failed.

Single prolactin values are unreliable — stress of venesection, recent sexual intercourse, and exercise all transiently raise prolactin. Repeat a mild or unexpected elevation on a rested sample and request macroprolactin exclusion from the lab; imaging is specialist-directed in clinical context.

Bone health in POI matters because oestrogen deficiency increases fracture risk. Arrange DXA according to baseline fracture risk and local menopause/POI guidance rather than automatically or urgently for every new diagnosis.

Refer

Referral Criteria — Who, Where, How Urgently

Done

Most amenorrhoea can be initiated in primary care. Know when specialist input is needed and how urgently.

999

Haemodynamic instability (ectopic) · Pituitary apoplexy (sudden headache + visual loss) · Adrenal crisis · Severe malnutrition with arrhythmia

Same-day

Suspected ectopic pregnancy (pain + βhCG positive) → A&E / Early Pregnancy Unit · Pituitary mass with visual field defect → A&E / on-call endocrinology · Severe eating disorder / malnutrition (haemodynamic compromise, electrolyte abnormality, very low or rapidly falling weight) → MEED pathway (RCPsych 2022)

Urgent

Rapid virilisation, clitoromegaly, deepening voice or markedly elevated androgens → urgent Gynaecology / Endocrinology referral (suspected androgen-secreting tumour) · No breast development by age 13, abnormal genital development, cyclic pelvic pain (outflow obstruction) or Turner features → Paediatric/adolescent gynaecology or endocrinology · Acute pelvic obstruction → emergency

Prompt specialist

Confirmed POI <40 yrs → specialist menopause/reproductive medicine, particularly for diagnostic uncertainty, fertility planning, complex comorbidity or suspected genetic/autoimmune disease; prompt fertility counselling · Persistent unexplained or markedly elevated prolactin, or symptoms suggesting pituitary disease → Endocrinology · Primary amenorrhoea (no menarche by 15 or >3 years after breast development) → Gynaecology — do not wait until 16

Routine

PCOS (uncomplicated, no fertility concerns) → Manage in primary care (International PCOS guideline 2023) · Hypothalamic amenorrhoea with identifiable cause (weight, exercise, stress) → Dietitian / CAMHS / exercise physiology referral as appropriate · Thyroid-related → treat thyroid, recheck cycle

Multidisciplinary

Eating disorders → CAMHS (under 18) / Adult ED team + dietitian + GP. Fertility desire with any cause → Gynaecology / Reproductive medicine. Athletes with RED-S → Sports medicine + dietitian

Who manages what

GP manages: PCOS (diagnosis + metabolic management), hypothalamic functional amenorrhoea (lifestyle), drug-induced (stop drug), thyroid-induced (treat thyroid), HRT/CHC in confirmed POI with specialist input as needed
Secondary care: Prolactinoma (cabergoline dosing), Turner's, MRKH, Asherman's, fertility treatment, primary amenorrhoea workup

POI diagnosis <40 carries significant long-term consequences — cardiovascular disease, osteoporosis, premature cognitive decline — that are substantially mitigated by HRT or CHC continued until at least the usual age of menopause (around 50–51). Early gynaecology input ensures timely fertility counselling and bone protection.

Prolactinoma management with dopamine agonists (cabergoline) is highly effective but requires specialist dosing, monitoring (echocardiography at high doses for valvulopathy), and MRI follow-up. GPs should initiate the referral, not the treatment.

NICE NG23 and the ESHRE POI guideline (2024, international) set out standards for POI management including bone health assessment according to fracture risk, cardiovascular risk assessment, and psychological and sexual health support.

Treat

Treatment Pathways by Cause

Done

Treatment is cause-specific — match the treatment to the diagnosis. Treating the underlying cause often restores menstruation without further hormonal intervention.

PCOS — Cycle Regulation

Combined hormonal contraceptive Option

For irregular cycles and hyperandrogenic symptoms if no contraindications — assess VTE, migraine, hypertension, smoking, BMI and other UKMEC factors. Co-cyprindiol is not first-line: reserve for severe androgen-related symptoms after considering VTE risk and alternatives

POI / Surgical Menopause

HRT or CHC Once POI confirmed

Offer HRT or a suitable combined hormonal contraceptive unless contraindicated (NICE NG23). If the uterus is present, prescribe adequate progestogen for endometrial protection according to the oestrogen dose, regimen and current menopause guidance — sequential or continuous combined HRT, or a 52 mg levonorgestrel IUS with systemic oestrogen; confirm the local menopause formulary and product information. HRT is not contraceptive; a CHC may be preferred if contraception is needed, but do not combine CHC with HRT without specialist advice. Continue until at least the usual age of menopause (~50–51)

Hypothalamic (Functional)

Address root cause — NOT hormones 1st Line

Individualised restoration of energy balance through an eating-disorder, dietetic, sports-medicine and psychological pathway as appropriate — BMI is not the sole target · Adjust excessive exercise · Stress management. Assess bone health and fracture risk, especially with prolonged amenorrhoea or stress fractures. Hormonal therapy does not correct the energy deficit or reliably restore fertility — specialist input if amenorrhoea persists

Drug-induced hyperprolactinaemia

Stop / switch causative drug 1st Line

Discuss with prescribing team — often switch antipsychotic to quetiapine (less prolactin elevation). Do NOT start dopamine agonists without specialist guidance

PCOS — Metabolic / Fertility Escalation Ladder

Step 1 Lifestyle modification — Weight loss of 5–10% if overweight can restore ovulation. Evidence-based

Step 2 Metformin — mainly for metabolic outcomes (impaired glucose regulation, metabolic syndrome or higher BMI) alongside lifestyle intervention, not first-line solely for BMI >25 or presumed insulin resistance. 500 mg OD with food, titrate gradually. Address GI adverse effects, renal function and B12 deficiency risk Intl PCOS guideline 2023

Step 3 Fertility (anovulatory PCOS, no other infertility factors) — specialist/reproductive medicine only: letrozole is the preferred first-line ovulation-induction treatment (Intl PCOS guideline 2023). Not prescribed from general practice as a routine step

Step 4 Clomifene (± metformin) — alternative where letrozole is contraindicated, unavailable or not used locally; not beyond 6 cycles; ultrasound monitoring where appropriate to reduce multiple-pregnancy risk. Or gonadotrophin injections (FSH) — reproductive medicine unit only

Step 5 IVF if above fails or tubal/male factor co-present. OHSS risk higher in PCOS — antagonist protocol preferred. Egg freezing if future fertility at risk (POI)

Prolactinoma — Dopamine Agonist Therapy (Secondary Care)

First-line

Cabergoline — specialist-initiated and dosed (SPC). Preferred over bromocriptine (better tolerability). Prolactin monitoring per endocrine plan

Monitoring

Endocrine-directed prolactin and MRI schedule · echocardiographic surveillance per specialist/SPC guidance (valvulopathy risk at higher doses)

Bone protection

POI from any cause: ensure adequate calcium (700–1000 mg/day dietary) + vitamin D 800–2,000 IU daily. DXA according to baseline fracture risk (e.g. prolonged amenorrhoea, stress fractures) and local guidance. HRT/CHC if oestrogen deficient

Next steps: see PCOS · Menopause and HRT · Eating disorders · Contraception

Treating functional hypothalamic amenorrhoea with hormones alone does not restore ovulation or fertility — it masks the problem. First-line treatment is restoring energy availability (adequate intake, adjusted training, stress reduction). The combined pill is not recommended to protect bone in FHA; if periods do not return after an adequate trial of nutritional, psychological and exercise change, the Endocrine Society FHA guideline (2017) suggests short-term transdermal 17β-estradiol with cyclical oral progestogen (specialist-guided). A 2026 meta-analysis of randomised trials (JCEM) found bone-density benefit with transdermal oestrogen but not with oral oestrogen or the combined pill.

HRT route in POI is a shared decision — NICE NG23 does not mandate a route; consider transdermal oestradiol, especially with VTE or stroke risk factors (e.g. raised BMI, migraine with aura), because oral oestrogen carries a higher VTE risk due to first-pass liver metabolism. Transdermal delivers oestrogen without hepatic activation of clotting factors. With a uterus, progestogen must be adequate for the oestrogen dose and regimen. NICE NG23 offers a choice of HRT or a combined hormonal contraceptive; many specialists prefer HRT because the COCP suppresses FSH without providing physiological oestrogen replacement and needs a pill-free interval.

Metformin in PCOS is used mainly for metabolic outcomes alongside lifestyle change; ovulation induction for fertility is specialist care, with letrozole first-line (Intl PCOS guideline 2023).

Lifestyle

Non-Pharmacological Interventions — These Are Treatment

Done

Lifestyle is first-line for functional amenorrhoea and essential alongside medical treatment for PCOS and POI. Frame this as treatment, not optional advice.

Energy balance (functional / low BMI) Individualised nutritional rehabilitation through dietetic, eating-disorder and psychological pathways as appropriate — no single BMI or calorie target. Most effective intervention for hypothalamic amenorrhoea.

Training and energy availability (RED-S) Individualised adjustment of training and intake with sports medicine + dietitian (and psychology where needed) — no fixed training reduction or universal energy availability target. Assess bone health and fracture risk, especially with stress fractures.

Stress reduction Hypothalamic GnRH is suppressed by cortisol. Psychological therapy (CBT), mindfulness-based stress reduction (MBSR), adequate sleep (7–9h). Quantify: validated perceived stress scale (PSS-10) at baseline.

Weight loss in PCOS (if overweight) 5–10% weight loss restores ovulation in up to 55% of overweight women with PCOS without medication. 1200–1500 kcal/day Mediterranean-style diet. Refer to structured weight management programme (NHS Tier 2).

Diet quality — PCOS metabolic Low glycaemic index diet reduces insulin, improves androgen profile. Avoid ultra-processed food, refined carbohydrates, sugar-sweetened drinks. Increase fibre ≥25 g/day. Evidence: reduces fasting insulin by 10–20%.

Bone health (all — especially POI) Dietary calcium ≥700 mg/day (dairy, fortified plant milks, leafy greens). Vitamin D supplement 800–2,000 IU/day (20–50 mcg; ROS 2020). Weight-bearing exercise 30 min/day (walking, resistance). Smoking cessation — smoking reduces oestrogen and accelerates bone loss.

Smoking cessation Smoking reduces oestrogen levels, advances menopause by 1–2 years, and accelerates bone density loss. Refer to NHS Stop Smoking Service. Varenicline or combination NRT (long-acting patch + short-acting product), with behavioural support, are the most effective options (NICE NG209).

Alcohol reduction Alcohol disrupts GnRH pulsatility and liver oestrogen metabolism. Aim <14 units/week. Alcohol excess can cause hyperprolactinaemia directly.

Psychological support Amenorrhoea has significant psychological impact — body image, identity, fertility anxiety. Refer to NHS Talking Therapies for anxiety/depression. Eating disorder specialist for suspected AN/BN. Fertility counselling if desired.

Contraception awareness (hypothalamic / PCOS) Ovulation may return unpredictably before menses resumes — counsel about unintended pregnancy risk. Provide contraceptive advice if not wanting pregnancy. "No periods ≠ no ovulation".

For functional hypothalamic amenorrhoea, lifestyle IS the treatment — hormonal therapy does not restore the hypothalamic-pituitary axis, does not restore fertility, and does not adequately protect bone density in the context of ongoing energy deficiency. The Endocrine Society FHA guideline (2017, international) is explicit: restoring energy balance and stress reduction are first-line, individualised through eating-disorder, dietetic, sports-medicine and psychological input; hormone therapy is adjunct only.

PCOS and weight: A 5% reduction in body weight in an overweight woman with PCOS reduces testosterone by 30%, LH by 40%, and fasting insulin by 40% (Norman et al.). This outperforms any single medication at this magnitude of effect.

Bone risk in amenorrhoea: Each year of amenorrhoea results in 2–4% bone density loss — equivalent to accelerated ageing. This is reversible with early intervention but not fully reversible after 5+ years. The window for bone protection matters.

Safety

Follow-Up, Monitoring & Safety-Netting

Done

Follow-up intervals depend on diagnosis and treatment. Always safety-net — amenorrhoea can unmask serious evolving pathology over time.

4–6 weeks

Review blood results · Confirm pregnancy test done · Assess treatment tolerability (COCP / HRT side effects) · Check BMI trend if functional / eating disorder · Dietary / exercise diary review

3 months

Reassess diagnosis if menses not returned · Repeat prolactin if previously elevated · Review metformin tolerance in PCOS · Second FSH 4–6 weeks after the first only if POI is being diagnosed · Assess psychological wellbeing

6 months

PCOS: weight/BMI, BP, glycaemic assessment and lipids according to baseline risk and local PCOS guidance · POI: bone health reviewed (DXA by fracture risk) · Prolactinoma: endocrine-directed prolactin monitoring · Hypothalamic: BMI achieved, exercise status, ovulation return?

Annual

PCOS: BMI, BP, glycaemic and lipid assessment by risk · POI: review HRT efficacy, adverse effects and bleeding pattern, symptoms, bone health, cardiovascular risk, fertility · Hypothalamic: weight/energy availability, mental health, bone risk · All amenorrhoea: Fertility intentions — refer if conceiving desired · Blood pressure if on COCP

Long-term (POI)

HRT or CHC continued until at least the usual age of menopause (~50–51). DXA according to fracture risk and local menopause/POI guidance, not automatically every 2–3 years. Autoimmune/genetic evaluation as specialist-guided. Monitor mood, cardiovascular risk and sexual function. HRT is not contraceptive.

Safety-net 999

Sudden severe headache + visual loss (pituitary apoplexy) · Collapse, hypotension (adrenal crisis) · Severe malnutrition with collapse or arrhythmia · Severe chest / shoulder pain with positive βhCG (ectopic rupture)

Safety-net same-day

New galactorrhoea · Rapid onset virilisation · Pelvic pain + positive βhCG · Severe electrolyte disturbance (eating disorder) · Visual field change (any cause) · Severe cyclical pelvic pain or suspected outflow obstruction/haematometra · OHSS symptoms if on ovulation induction (abdominal distension, vomiting, reduced urine output)

Safety-net routine

No menstrual return after 6 months appropriate treatment → repeat investigations, reconsider diagnosis · Weight not improving despite dietitian input → eating disorder team · New symptoms of depression / anxiety → psychological support / medication

Fertility monitoring

If fertility desired: document desire at each contact, ensure referral timely (age matters). Do not wait 12 months before referral if there is known anovulation, POI, a significant endocrine disorder, severe endometriosis, tubal disease, male-factor concern or age-related fertility concern. POI: refer promptly for fertility counselling — spontaneous intermittent ovarian activity can occur; donor egg counselling may be needed.

Contraception

Women not wanting pregnancy who begin treatment (especially lifestyle for hypothalamic or metformin for PCOS) must be counselled that ovulation may return before menses — advise reliable contraception from treatment commencement. In POI, HRT does not prevent conception and is not contraceptive

Amenorrhoea is not a benign symptom — untreated POI increases fracture and cardiovascular disease risk over a lifetime. Monitoring should be diagnosis-specific and follow local specialist guidance.

The contraception paradox: Women who present with amenorrhoea often assume they are not fertile. When treatment is initiated (lifestyle, metformin, cabergoline), ovulation can return unpredictably — sometimes before the first period returns. Unplanned pregnancy rates in treated amenorrhoea are well-documented. This must be discussed at every treatment initiation.

Prolactinoma surveillance: Microprolactinomas rarely enlarge (<5% over 10 years) but macroprolactinomas can. If the patient stops cabergoline, prolactin is rechecked according to the endocrine plan, as recurrence after stopping is common.

Eating disorders and GP follow-up: GPs hold a crucial relationship with these patients. Even when under specialist care, regular GP review enables monitoring of vital signs, weight, and electrolytes — and provides continuity that specialists cannot. Do not hand over completely.

🌸 Amenorrhoea

Red Flags & Urgent Exclusions — Act First

Confirm Type — Primary vs Secondary Amenorrhoea

Classification — Identify the Underlying Cause

Targeted Clinical Examination

Investigations — Stepwise Approach

Referral Criteria — Who, Where, How Urgently

Treatment Pathways by Cause

Non-Pharmacological Interventions — These Are Treatment

Follow-Up, Monitoring & Safety-Netting