Why Fatigue History Is Tested in OSCEs
Fatigue is one of the most common presenting complaints in general practice, accounting for approximately 10% of consultations. It is an ideal OSCE station because it tests diagnostic breadth, systematic thinking, and the ability to identify both serious organic pathology and functional/psychological causes without dismissing either. Candidates who treat it as "nothing" consistently underperform; those who apply a structured screen impress examiners.
Opening and Establishing the Symptom
Begin open: "Can you tell me more about this tiredness you've been experiencing?" Clarify the patient's own language — tiredness, fatigue, sleepiness, weakness, and lethargy are different. Establish:
- Onset and duration (weeks vs. months vs. years)
- Pattern (constant vs. intermittent; worse at particular times of day)
- Severity (impact on daily activities — can they work, exercise, socialise?)
- Change over time (progressive vs. stable vs. fluctuating)
The Systematic Differential Screen
Use an organ-system approach and screen each major category explicitly:
Haematological — Anaemia
Ask about: pallor, breathlessness on exertion, palpitations, dizziness, cold intolerance. Explore for the cause of anaemia: diet (iron, B12, folate intake), menstrual history (heavy periods = iron loss), GI symptoms (bleeding — melaena, haematochezia), alcohol, malabsorption (coeliac — diarrhoea, bloating, mouth ulcers), medication (methotrexate causing folate deficiency, PPIs reducing iron absorption).
Endocrine — Hypothyroidism
Fatigue, weight gain, constipation, cold intolerance, dry skin, hair loss, bradycardia, depression, menstrual irregularity. Ask: "Have you noticed feeling colder than usual, or putting on weight without changing your diet?"
Endocrine — Diabetes
Polyuria, polydipsia, weight loss (Type 1), nocturia, blurred vision, recurrent infections. Screen: "Have you been drinking more water or passing more urine than usual?"
Mental Health — Depression
Depressed mood, anhedonia (inability to feel pleasure), sleep disturbance, appetite changes, poor concentration, feelings of worthlessness. Use PHQ-2 screening: "Over the past two weeks, have you felt down, depressed, or hopeless? Have you had little interest or pleasure in doing things?" A positive screen requires a full PHQ-9.
| Organic vs. Functional Fatigue Feature | Organic | Functional/Psychological |
|---|---|---|
| Time of day pattern | Variable | Often worse in morning |
| Sleep | Non-restorative | Hypersomnia or insomnia |
| Mood | Usually intact | Low mood, anhedonia |
| Life events | Absent | Often present |
| Exertional worsening | Variable | Post-exertional malaise (ME/CFS) |
Cardiac — Heart Failure
Breathlessness (exertional, orthopnoea, PND), ankle swelling, reduced exercise tolerance, nocturnal cough. Risk factors: hypertension, IHD, valve disease.
Renal — Chronic Kidney Disease
Often asymptomatic until advanced. Ask about known CKD, hypertension, diabetes, oedema, reduced urine output, pruritis, nausea.
Malignancy
Constitutional symptoms: unexplained weight loss (>5% in 3 months), drenching night sweats, persistent fever, lymphadenopathy, haemoptysis, haematuria, altered bowel habit. Perform a full systems review for localising symptoms.
Sleep Disorders — OSA
Snoring (ask partner), witnessed apnoeas, morning headaches, excessive daytime sleepiness (Epworth Sleepiness Scale), waking unrefreshed, obesity, collar size >17 inches (men).
Other Causes
Infection (post-viral fatigue, TB, hepatitis), autoimmune (SLE, RA, PMR), medication side-effects (beta-blockers, antidepressants, antihistamines, statins), adrenal insufficiency, haemochromatosis, coeliac disease.
Red Flags — Urgent Investigation
⚠️ Red Flag
Red flags: unexplained weight loss, haemoptysis, haematuria, altered bowel habit, lymphadenopathy, night sweats, persistent fever, new neurological symptoms. Any of these alongside fatigue mandates urgent investigation for malignancy.
Systems Review
Complete a thorough systems review: cardiovascular, respiratory, GI (appetite, weight, bowel habit), GU, MSK, neurological, skin, ENT.
Social History
Occupation and sick leave, exercise tolerance (baseline vs. now), sleep pattern, diet, alcohol, caffeine, recreational drugs, stressors, life events, support at home.
ICE and Quality of Life
Always explore: "What do you think might be causing this?" — patients often have their own hypothesis (cancer fear is common). "How much is this affecting your daily life?" — fatigue is often the most disabling symptom the patient experiences but is under-reported.
Investigations to Mention
First-line: FBC, ferritin, B12 and folate, TFTs, HbA1c, fasting glucose, U&Es, LFTs, eGFR, CRP/ESR, calcium. Targeted: coeliac antibodies (tTG-IgA), ANA, RF, PSA, TB testing (IGRA/Mantoux), hepatitis serology, iron studies (ferritin). Sleep: Epworth Sleepiness Scale, sleep study (polysomnography) if OSA suspected.
Frequently Asked Questions
"What is the most systematic way to approach a fatigue history in an OSCE without missing causes?"
Use an organ-system mnemonic to structure your screen. One approach: HEMATINS — Haematological (anaemia), Endocrine (thyroid, diabetes, adrenal), Mental health (depression, anxiety), Autoimmune/chronic infection, Tumour/malignancy, Infection (viral, TB, hepatitis), Nutritional/medications, Sleep (OSA, insomnia). Start with the most common causes in the relevant demographic — in a young woman the most likely causes are iron-deficiency anaemia, depression, and hypothyroidism; in an older man add malignancy, cardiac failure, and CKD to the top of the list. This demonstrates diagnostic reasoning tailored to the patient, not just a rote list.
"How do I screen for depression in a fatigue history without being intrusive?"
Introduce the topic naturally: "Feeling tired for a long time can really affect your mood. I'd like to ask about how you've been feeling in yourself — is that okay?" Then use the PHQ-2 screening questions: "Over the past two weeks, how often have you felt down, depressed, or hopeless?" and "Over the past two weeks, how often have you had little interest or pleasure in doing things?" If either screen is positive (scoring 2 or more on a 0–3 scale), proceed to the full PHQ-9. In an OSCE, simply asking the two PHQ-2 questions explicitly and linking them to fatigue scores highly for mental health integration. Avoid asking "are you depressed?" — this is closed, leading, and often triggers denial.
"What features in the history suggest obstructive sleep apnoea as a cause of fatigue?"
OSA should be suspected when fatigue is specifically described as excessive daytime sleepiness — the patient falls asleep easily and unintentionally during the day (at meetings, watching TV, driving — the last being a DVLA notification issue). The Epworth Sleepiness Scale quantifies this: score >10 is abnormal, >16 is severe. Key associated features: loud snoring (often reported by a partner), witnessed apnoeas (partner notices breathing stops), waking unrefreshed despite adequate sleep time, morning headache (CO2 retention), and nocturia. Risk factors: male sex, obesity (BMI >30), large neck circumference (>17 inches in men, >16 in women), craniofacial abnormalities, alcohol use, and hypothyroidism (causes muscular hypotonia). The STOP-BANG questionnaire (Snoring, Tired, Observed apnoeas, Pressure/hypertension, BMI >35, Age >50, Neck >40 cm, Gender male) is a useful screening tool — mention it to impress examiners.
"What blood tests would you request for a patient presenting with tiredness and why?"
A comprehensive first-line screen should include: FBC (anaemia — type and severity; thrombocytopaenia/leucocytosis suggesting haematological malignancy); ferritin (iron stores — note it is an acute phase reactant and may be falsely elevated in inflammation); B12 and folate (deficiency causes macrocytic anaemia and neurological symptoms); TFTs — TSH ± free T4 (hypothyroidism is a common missed cause, especially in women); HbA1c (screen for diabetes); U&Es and eGFR (CKD); LFTs (liver disease, haemochromatosis); CRP and ESR (non-specific markers of inflammation/infection/malignancy); calcium (hypercalcaemia causes fatigue, constipation, depression — "bones, stones, groans, psychic moans"). If indicated by the history: coeliac antibodies (tTG-IgA), hepatitis B and C serology, ANA (SLE), RF and anti-CCP (RA), CK (myopathy), morning cortisol (Addison's), iron studies (haemochromatosis).
"How do I distinguish post-viral fatigue from depression in the history?"
Post-viral fatigue (including ME/CFS) typically follows a clear viral trigger (often an URTI, glandular fever, or COVID-19), has a specific onset date the patient can identify, and is characterised by post-exertional malaise (PEM) — symptoms worsen predictably after physical or cognitive exertion, often with a delayed response (crashing 24–48 hours after activity). Sleep is non-restorative, and the patient wakes feeling unrefreshed. Cognitive symptoms ("brain fog") are prominent. Depression, by contrast, is characterised by persistent low mood and anhedonia, is not typically linked to a clear viral trigger, and does not always feature PEM. Sleep disturbance in depression is often early morning wakening or initial insomnia. Both can coexist — ME/CFS is associated with comorbid depression in ~30–50% of cases — so screen for both in every fatigue history.
"What medications cause fatigue and how do I take a drug history for this?"
Many commonly prescribed drugs cause fatigue as a side-effect and should be systematically reviewed. Beta-blockers cause fatigue and exercise intolerance due to reduced cardiac output and blunted heart rate response. Antihistamines (especially first-generation: chlorphenamine, promethazine) cause sedation. Antidepressants (SSRIs, TCAs, mirtazapine) and benzodiazepines cause fatigue. Statins cause fatigue and myalgia in up to 10% of patients — check CK if suspected. Opioids, antiepileptics (valproate, pregabalin), and antipsychotics all cause sedation. Corticosteroids cause proximal myopathy with muscle weakness and fatigue with long-term use. In the OSCE, explicitly going through the drug history and asking "could any of these be causing your tiredness?" demonstrates clinical awareness and often reveals a reversible cause.
Related guides: Anaemia History OSCE · Depression and Anxiety History OSCE · Thyroid History OSCE · Weight Loss History OSCE · Diabetes History OSCE