Differentials
| System |
What might it be? |
What might I find? |
|
| Endocrine |
Hypothyroidism |
Hashimoto’s, iodine deficiency’s, over treated thyrotoxicosis, amiodarone.
Sx: Fatigue, constipation, weight gain, dry skin, coarse hair, menorrhagia, goitre. |
|
|
Cushing’s Syndrome |
Caused by exposure to prolonged ↑glucocorticoid (e.g., cortisol) levels.
Causes: Cushing’s disease, adrenal adenoma, paraneoplastic syndrome (e.g., small cell lung ca), exogenous steroid. Cushing’s disease: pituitary adenoma, ↑ACTH, stimulates adrenal ↑cortisol. Adrenal adenoma: ↑adrenal cortisol, ↓ACTH secondary to negative feedback. Paraneoplastic syndrome: ↑ACTH, stimulates adrenal ↑cortisol. Exogenous steroid: ↑cortisol, ↓ACTH secondary to negative feedback. Sx: round face, central obesity, buffalo hump, proximal limb muscle wasting, hirsutism, abdominal striae, easy bruising; skin hyperpigmentation if ↑ACTH, headache and bitemporal hemianopia if pituitary adenoma. Assoc: hypertension, cardiac hypertrophy, T2DM, dyslipidaemia, osteoporosis. |
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|
Acromegaly |
Exposure to excess growth hormone. Causes: pituitary adenoma, para-neoplastic syndrome (e.g., neuroendocrine tumour (NET)).
Sx: frontal skull bossing, enlarged nose tongue, hands, feet, and jaw; headache and bitemporal hemianopia if pituitary adenoma. Assoc: hypertension, cardiac hypertrophy, T2DM, carpal tunnel, colorectal ca. |
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|
Polycystic Ovarian Syndrome |
Oligomenorrhoea, hyperandrogenism, and polycystic ovaries on USS (2/3 req).
Sx: irregular periods, sub fertility, obesity, hirsutism, acne, male pattern hair loss, insulin resistance, metabolic syndrome, acanthosis nigricans, low mood. ↑LH, ↑LH:FSH ratio, ↑testosterone, polycystic ovary appearance on USS. |
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| Physiological |
Puberty |
Average age: 12 (males), 11 (females); normal 9-14 (males) and 8-13 (females).
Male: deep voice, pubic hair, growth of penis/testicles, ↑weight (muscle). Female: breast development, pubic hair, menarche, ↑weight (fat at hips/breasts). Average weight gain: 15kg (males), 14 kg (females). |
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|
Pregnancy |
Weight of baby, amniotic fluid, uterus, placenta, fluid retention, increase in fat storage to aid breastmilk production, increased circulating blood volume.
Average weight gain in pregnancy 10-12.5kg. Generally gained 20/40 onwards. |
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|
Perimenopause |
↓ oestrogen, ↑visceral fat, ↓lean muscle, ↓metabolic rate, ↑sedentary lifestyle.
Average weight gain is 1.5kg per year or 10kg average total weight gain. |
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| Lifestyle |
Overweight |
Defined as BMI 25-29.9 (23-27.4 if higher risk family background e.g., Chinese).
Complex cause including ↑calorie intake, ↑sedentary lifestyle & genetic factors. |
|
|
Obesity |
Defined as BMI >30 (>27.5 if higher risk family background e.g., Chinese).
Complex cause including ↑calorie intake, ↑sedentary lifestyle & genetic factors. |
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| Miscellaneous |
Fluid Overload |
Congestive cardiac failure, renal failure, nephrotic syndrome, pregnancy, chronic liver disease, hypoalbuminaemia, medication side effect including IV fluid. | |
|
Binge Eating Disorder |
Excessive over-eating due to psychological distress and loss of control.
Unlike bulimia, there is no purging thus patients likely to be overweight. Planned binge, bingeing even when full or not hungry, eating in dazed state. |
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Pharmacological |
Culprit medications include: antidepressants, exogenous hormones e.g., COCP, exogenous steroids, antipsychotic, insulin, sulfonylureas (e.g., gliclazide).
Alcohol consumption, smoking cessation can also cause ↑weight. |
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Checklist
| Preparation | Wash – Name – Explain | |
| Presenting Complaint | Open question to establish reason for presentation | |
| Allow patient time to talk uninterrupted | ||
| History of Presenting Complaint | Onset | |
| Character | ||
| Triggers | ||
| Associated symptoms | ||
| Lifestyle | ||
| Impact | ||
| System-specific | Headache | |
| Vision changes | ||
| Facial appearance changes | ||
| Skin changes | ||
| Goitre | ||
| Temperature tolerance | ||
| Bowel changes | ||
| Hirsutism | ||
| Menstrual cycle | ||
| Relevant Systems Review | Gynaecological | |
| Psychological | ||
| ICE | What do you think is going on? | |
| Is there anything that is worrying you? | ||
| What were you hoping we would do today? | ||
| Past Medical History | Past medical history | |
| Past surgical history | ||
| Drug History | Prescribed medication | |
| Over-the-counter medication | ||
| Drug allergies | ||
| Social History | Smoking | |
| Alcohol | ||
| Recreational drugs | ||
| Work | ||
| Driving | ||
| Who is at home? | ||
| Sick contacts | ||
| Forgeign travel | ||
| Family History | Do any family members have any endocrine problems? | |
| Do any health conditions run in the family? | ||
| Comm. Skills | Establish rapport | |
| Use open and closed questions appropriately | ||
| Structured history taking | ||
| Pick up on cues | ||
| Rule in/out differential diagnoses | ||
| Summarise succinctly |
Explanation
“I have been asked to speak to you today about the weight change you have been noticed. I will ask you some questions to try to determine what might be causing the problem. Does that sound all right?”
History of Presenting Complaint
Key points in a weight gain history include:
- Onset – when did the patient first notice they were gaining weight?
- Character
- Triggers – can they think of anything that may have caused the problem?
- Associated symptoms – have they noticed anything else alongside the weight change?
- Lifestyle (e.g., diet, exercise)
- Impact – on the patient, their self-esteem, body image, etc.
When was the onset of weight gain? Normal physiological weight gain can occur at puberty, during pregnancy, and perimenopause.
Ask about the character of the weight change. Has it affected specific body areas (e.g., central obesity in Cushing’s syndrome, or growth of the hands and feet in acromegaly), or is it generalised weight gain (e.g., obesity, hypothyroidism)?
Is the weight being carried as muscle (e.g., male puberty), fluid (e.g, oedema), or fat?
Is the patient able to quantify the weight gain? How much weight have they gained over what period of time? If their height is known, their body mass index (BMI) can be calculated.
Ask about lifestyle, including diet and physical activity. Is there a calorie excess and a sedentary lifestyle (overweight or obesity), or a calorie deficit and an active lifestyle (may indicate an endocrine cause)?
System-specific History
Endocrine symptoms to enquire about include, but are not limited to:
- Headaches (e.g., pituitary adenoma causing Cushing’s disease or acromegaly)
- Vision changes (e.g., bitemporal hemianopia with pituitary adenoma)
- Facial appearance changes (e.g., moon face in Cushing’s syndrome; prominent jaw, forehead, and ears in acromegaly)
- Skin changes (e.g., striae and easy bruising in Cushing’s syndrome; coarse skin in acromegaly; dry skin in hypothyroidism; acne in polycystic ovarian syndrome (PCOS ) and puberty)
- Goitre (e.g., Hashimoto’s thyroiditis)
- Temperature tolerance (e.g., cold intolerance in hypothyroidism)
- Bowel changes (e.g., constipation in hypothyroidism)
- Hirsutism (associated with PCOS and Cushing’s syndrome)
- Menstrual cycle (menorrhagia associated with hypothyroidism; oligomenorrhoea occurs in PCOS)
Relevant Systems Review
Relevant systems to review when taking a history of weight gain include the following:
- Gynaecological
- Psychological (depression, antidepressants e.g., SSRIs, and binge-eating disorder).
Heavy menstrual bleeding (menorrhagia) may be associated with hypothyroidism. PCOS can cause oligomenorrhoea, or even amenorrhoea.
Menarche is the onset of menstruation at puberty. Perimenopause may cause menstrual changes until menopause (defined as the cessation of periods for >12 months).
Ideas, Concerns & Expectations (ICE)
Does the patient have any thoughts as to what might be causing their weight gain?
Is the patient worried about their symptoms (e.g., the possibility of a serious underlying cause such as cancer)?
What does the patient want from the consultation (e.g., a blood test, medication)?
Past Medical History
Pre-existing medical conditions that may be associated with weight gain include:
- Chronic disease causing fluid retention (e.g., chronic liver disease, chronic heart failure, or chronic kidney disease)
- Depression (as a condition or due to medication side effects).
Drug History
Common pharmacological causes of weight gain include:
- Antidepressants (e.g., SSRIs or mirtazapine)
- Exogenous hormones (e.g., combined oral contraceptive pill)
- Diabetic medications (e.g, insulin, sulfonylureas)
- Steroids (weight gain is a known side effect; long-term use can also cause Cushing’s syndrome)
Social History
Alcohol can cause weight gain through multiple mechanisms including calorie intake, appetite stimulation, and metabolic changes.
Smoking cessation is associated with weight gain.
Does the patient drive? The DVLA must be informed if the patient has a bitemporal hemianopia.
Family History
Several conditions associated with weight gain have a genetic predisposition:
- PCOS
- Thyroid disease
- Overweight
- Obesity
Finishing
Thank the patient and wash your hands.
Consider your differential diagnosis and how you might narrow this down further through examination, bedside tests, or further investigation and imaging.
Last updated July 2025
Head to members.zerotofinals.com for practice OSCE stations, including an interactive checklist, specific cases and clinical findings.
