Weight loss in an adult
Unintentional weight loss always has a cause. In most first-level settings the big four are TB, HIV, diabetes and cancer, and two of them can be present together. A careful history, a finger-prick and a rapid test usually show the way; the skill is in not stopping at the first answer.
- Setting: Urban health centre in a country with high TB and HIV burden
- For clinical officers, nurses and doctors at first-level facilities
- Reviewed October 2026
The presentation
Peter, 46, drives a minibus. His wife says his clothes have become loose. He weighed 78 kg at a check-up 3 months ago; today he weighs 70 kg. He feels tired all the time and is always thirsty.
| Measurement | Value |
|---|---|
| Weight | 70 kg (78 kg 3 months ago) |
| Height | 172 cm (BMI 23.7) |
| Blood pressure | 138/86 mmHg |
| Pulse | 92 per minute |
| Temperature | 36.7 °C |
| Breathing rate | 16 per minute |
Tests at hand: Blood glucose (finger-prick) · Urine dipstick · HIV rapid test · Haemoglobin (Hb) · Sputum sample sent for a rapid molecular TB test
- DiabetesStill possible
- Tuberculosis Must not missStill possible
- HIV infection Must not missStill possible
- Cancer (for example stomach, bowel, oesophagus) Must not missStill possible
- Diabetic ketoacidosis or hyperosmolar state Must not missStill possible
- Overactive thyroid (thyrotoxicosis)Still possible
- Depression or alcohol useStill possible
- Poor intake (food insecurity, swallowing problems)Still possible
Work through it
Read each question and decide your own answer first. Then open the model answer and see how the differential changes.
- Step 1 of 7 · Look
Is the weight loss significant, and is Peter unwell enough to need emergency care?
Model answer
WHO calls a loss of 5% or more of body weight over 6 months significant. Peter has lost 8 kg of 78 kg, about 10%, in 3 months: this needs a cause found.
He walked in and his vital signs are normal. Ask straight away about the warning signs of a diabetes emergency: vomiting, abdominal pain, deep fast breathing, drowsiness. He has none. He is not an emergency, but he is a priority for assessment today.
A normal BMI does not mean the loss does not matter. Compare with his own previous weight.Differential now- DiabetesStill possible
- Tuberculosis Must not missStill possible
- HIV infection Must not missStill possible
- Cancer (for example stomach, bowel, oesophagus) Must not missStill possible
- Overactive thyroid (thyrotoxicosis)Still possible
- Depression or alcohol useStill possible
- Diabetic ketoacidosis or hyperosmolar state Must not missLess likely (moved down)
- Poor intake (food insecurity, swallowing problems)Less likely (moved down)
- Step 2 of 7 · Ask
Which questions work through the main causes of weight loss?
Model answer
- Diabetes: thirst, passing a lot of urine, waking at night to pass urine, blurred vision, hunger, infections.
- TB (the WHO four-symptom screen): current cough, fever, night sweats, weight loss. Any one means possible TB. Ask about contact with someone with TB.
- HIV: previous tests, risk, recurrent infections, chronic diarrhoea, skin rash, mouth sores.
- Cancer: difficulty swallowing, indigestion of recent onset, vomiting, change in bowel habit, blood in stool or urine, a lump, a cough with blood, persistent hoarseness.
- Thyroid: palpitations, heat intolerance, sweating, tremor.
- Mood, alcohol and food: appetite, low mood, how much he drinks, whether the family has enough food.
Peter has been very thirsty for 2 months and gets up 4 times a night to pass urine. His appetite is good. No cough, fever or night sweats; no known TB contact. Never tested for HIV. No swallowing problems, indigestion or change in bowels; no blood. No palpitations or tremor. Mood is fine. Two beers at the weekend; smokes 10 cigarettes a day. His mother had diabetes.
Differential now- DiabetesLeading (moved up)
- HIV infection Must not missStill possible
- Tuberculosis Must not missLess likely (moved down)
- Cancer (for example stomach, bowel, oesophagus) Must not missLess likely (moved down)
- Diabetic ketoacidosis or hyperosmolar state Must not missLess likely
- Overactive thyroid (thyrotoxicosis)Less likely (moved down)
- Poor intake (food insecurity, swallowing problems)Less likely
- Depression or alcohol useSet aside for now (moved down)
- Step 3 of 7 · Look
What do you examine for, and why?
Model answer
- Lymph nodes in the neck, armpits and groin (TB, HIV, lymphoma).
- Mouth: thrush or hairy leukoplakia (HIV); dryness (dehydration).
- Thyroid swelling, eye protrusion, tremor, fast pulse (thyrotoxicosis).
- Chest: crackles or dullness (TB, effusion).
- Abdomen: liver, spleen, a mass, tenderness.
- Feet: sensation and skin, as for anyone suspected of diabetes.
No enlarged nodes. Mouth dry; no thrush. No goitre, no tremor. Chest clear. Abdomen soft, no masses, no enlarged liver or spleen. Feet: normal sensation and skin.
Differential now- DiabetesLeading
- HIV infection Must not missStill possible
- Tuberculosis Must not missLess likely
- Cancer (for example stomach, bowel, oesophagus) Must not missLess likely
- Diabetic ketoacidosis or hyperosmolar state Must not missLess likely
- Poor intake (food insecurity, swallowing problems)Less likely
- Overactive thyroid (thyrotoxicosis)Set aside for now (moved down)
- Depression or alcohol useSet aside for now
- Step 4 of 7 · Test
Which bedside tests do you do, and what result would change your plan?
Model answer
- Glucose (finger-prick, random): with typical symptoms, a random plasma glucose of 11.1 mmol/L (200 mg/dL) or more diagnoses diabetes without a second test.
- Urine dipstick: glucose and ketones. Ketones 2+ or more in someone who is unwell is a diabetes emergency.
- HIV rapid test, with consent: HIV is a common cause of weight loss and changes TB risk.
- Haemoglobin: anaemia would point towards blood loss (bowel or stomach cancer), HIV or TB.
- A sputum sample is not needed today: his TB symptom screen is negative apart from the weight loss, and the weight loss has a likely explanation. Keep it in mind (see step 6).
Results: random glucose 19.4 mmol/L. Urine glucose 3+, ketones trace. HIV test negative. Hb 14.2 g/dL.
Differential now- DiabetesLeading
- Tuberculosis Must not missLess likely
- Cancer (for example stomach, bowel, oesophagus) Must not missLess likely
- Poor intake (food insecurity, swallowing problems)Less likely
- HIV infection Must not missSet aside for now (moved down)
- Diabetic ketoacidosis or hyperosmolar state Must not missSet aside for now (moved down)
- Overactive thyroid (thyrotoxicosis)Set aside for now
- Depression or alcohol useSet aside for now
- Step 5 of 7 · Do
What is the diagnosis and how do you classify it? Could this be type 1 diabetes?
Model answer
Peter has diabetes: classic symptoms with a random glucose of 19.4 mmol/L. Ketones are under 2+ and he is well, so this is not ketoacidosis. In the WHO PEN and HEARTS-D protocol, glucose above 18 mmol/L with symptoms is symptomatic hyperglycaemia, treated at the health centre.
Think of type 1 diabetes (refer) if the person is young and lean, loses weight very fast, has ketones of 2+ or more, or does not respond to tablets. Peter is 46, with a family history and no significant ketones: type 2 diabetes is most likely.
Uncontrolled diabetes explains the thirst, the urine and the weight loss. Weight loss that continues once the glucose is controlled needs a new search.Differential now- DiabetesLeading
- Tuberculosis Must not missLess likely
- Cancer (for example stomach, bowel, oesophagus) Must not missLess likely
- HIV infection Must not missSet aside for now
- Diabetic ketoacidosis or hyperosmolar state Must not missSet aside for now
- Overactive thyroid (thyrotoxicosis)Set aside for now
- Depression or alcohol useSet aside for now
- Poor intake (food insecurity, swallowing problems)Set aside for now (moved down)
- Step 6 of 7 · Do
What do you start today, and how do you make sure TB and cancer are not missed?
Model answer
- Symptomatic hyperglycaemia: the WHO protocol starts metformin 1000 mg twice daily and gliclazide 80 mg twice daily together, with a review in 3 to 5 days. Teach him the signs of low glucose and what to do; driving is a risk if he becomes hypoglycaemic.
- Fluids: plenty of water while the glucose is high.
- Check BP, and plan a statin (he is over 40 with diabetes) and help to stop smoking.
- TB: diabetes increases the risk of TB. Repeat the four-symptom screen at every visit and send sputum for a rapid molecular test if any symptom appears.
- Weight: record it at each visit. If he keeps losing weight with good glucose control, look again: sputum for TB, a repeat HIV test if at risk, and referral to look for cancer.
Differential now- DiabetesLeading
- Tuberculosis Must not missLess likely
- Cancer (for example stomach, bowel, oesophagus) Must not missLess likely
- HIV infection Must not missSet aside for now
- Diabetic ketoacidosis or hyperosmolar state Must not missSet aside for now
- Overactive thyroid (thyrotoxicosis)Set aside for now
- Depression or alcohol useSet aside for now
- Poor intake (food insecurity, swallowing problems)Set aside for now
- Step 7 of 7 · Ask
What do you tell Peter, and when must he come back?
Model answer
- Come back in 3 to 5 days so the glucose can be checked and the doses adjusted.
- Come back at once if he vomits, has abdominal pain, breathes fast, or becomes drowsy (high glucose emergency), or if he is shaky, sweaty and confused (low glucose).
- Report a new cough, fever or night sweats at any visit.
- Food: regular meals, fewer sugary drinks; the nurse will go through a plan with him and his wife.
Your weight loss and thirst are caused by diabetes. These tablets will bring your sugar down and you should start to feel better within days. Come back in 4 days. If you start vomiting or feel very drowsy, come back straight away.
Must-not-miss conditions
| Condition | Clues | What to do at first-level care |
|---|---|---|
| Tuberculosis | Any of current cough, fever, night sweats or weight loss; TB contact; HIV or diabetes as risk factors; enlarged nodes. | Sputum for a rapid molecular test (urine LF-LAM in advanced HIV); repeat the symptom screen at each visit. |
| HIV infection | Weight loss over 10%, chronic diarrhoea or fever over a month, thrush, recurrent infections. | Offer an HIV test; if positive, start the ART pathway and screen for TB. |
| Cancer | Weight loss with difficulty swallowing, recent onset of indigestion, change in bowel habit, blood in stool or urine, anaemia, a lump or hard liver. | Refer for investigation; do not attribute continuing weight loss to another cause without review. |
| Diabetic ketoacidosis or hyperosmolar state | High glucose with vomiting, abdominal pain, deep fast breathing, dehydration or drowsiness; urine ketones 2+ or more. | Start 0.9% saline and refer now. |
Decision at first-level care
Peter has newly diagnosed type 2 diabetes with symptomatic hyperglycaemia (random glucose 19.4 mmol/L, ketones under 2+). HIV test is negative and the TB screen is negative apart from the weight loss. He starts metformin and gliclazide at the health centre with review in 3 to 5 days, and his weight and TB symptoms are tracked at every visit.
Source: WHO HEARTS-D (2020); WHO PEN (2020); WHO consolidated guidelines on tuberculosis, Module 2 (2021); IMAI district clinician manual, volume 2 (2011).
- Diabetes diagnosed, ketones under 2+, able to eat and drink, not acutely ill.
- Moderate undernutrition with a treatable cause and no danger sign.
- Small weight loss with a clear cause (recent illness, food shortage) and a normal examination: record weight and review in 4 weeks.
- Negative tests and no cause found yet: repeat weight and symptom screen in 2 to 4 weeks.
- Ketones 2+ or more, vomiting, drowsiness, or glucose that does not improve on treatment: now.
- Suspected type 1 diabetes.
- Red-flag symptoms of cancer: for investigation.
- Continuing weight loss with no cause found at first-level care.
- Severe undernutrition (adult MUAC under 160 mm, or 161 to 185 mm with oedema, inability to stand or sunken eyes) for therapeutic feeding.
Key learning points
- Weight loss of 5% or more in 6 months is significant; compare with the person's own earlier weight.
- Work through TB, HIV, diabetes and cancer in every adult with unexplained weight loss.
- With symptoms, a random glucose of 11.1 mmol/L or more diagnoses diabetes; check ketones to exclude an emergency.
- Diabetes raises the risk of TB: screen for TB symptoms at every diabetes visit.
- If the weight keeps falling once the first cause is treated, look for a second one.
Sources
- World Health Organization. IMAI district clinician manual: hospital care for adolescents and adults, volume 2. 2011. Section 10.3, weight loss: 5% or more over 6 months is significant; causes (TB, HIV, cancers, diabetes, thyrotoxicosis, substance use); assessment steps; adult MUAC criteria for severe undernutrition at health centre level.
- World Health Organization. Diagnosis and management of type 2 diabetes (HEARTS-D). 2020. Random plasma glucose 11.1 mmol/L with symptoms; symptomatic hyperglycaemia and the starting regimen; ketones 2+ as an emergency; statin from age 40 (as summarised in the type 2 diabetes protocol).
- World Health Organization. WHO package of essential noncommunicable (PEN) disease interventions for primary health care. 2020 (ISBN 9789240009226). Diabetes symptoms (polyuria, polydipsia, unexplained weight loss); common cancer warning symptoms by site.
- World Health Organization. WHO consolidated guidelines on tuberculosis. Module 2: screening – systematic screening for tuberculosis disease. 2021. Four-symptom screen (current cough, fever, weight loss, night sweats); diabetes as a TB risk factor.
- World Health Organization. Consolidated guidelines on HIV prevention, testing, treatment, service delivery and monitoring. 2021. Offering HIV testing to people with symptoms that may be related to HIV.