Undifferentiated Symptoms — MCQs

Understanding the concept of 'diagnostic uncertainty' in managing undifferentiated symptoms in primary care involves recognizing that certain presentations cannot be immediately diagnosed. Which of the following statements best describes the evidence-based approach to managing diagnostic uncertainty?

A 35-year-old woman presents with a 10-week history of severe fatigue, aching limbs, and subjective fever. She works as a veterinary nurse. She reports a flu-like illness that never fully resolved. Examination shows temperature 37.8°C, no rash or lymphadenopathy. Blood tests show: Hb 128 g/L, WCC 3.8 × 10⁹/L (lymphocytes 1.2 × 10⁹/L), platelets 156 × 10⁹/L, CRP 12 mg/L, ALT 124 U/L, AST 96 U/L. Blood film shows atypical lymphocytes. Monospot test is negative. What is the most appropriate next investigation?

A 66-year-old man with a 15-week history of fatigue and 8kg weight loss has been investigated extensively in primary care. Blood tests including FBC, U&E, LFT, TFT, calcium, glucose, CRP, and PSA are normal. Chest X-ray and abdominal ultrasound are unremarkable. He has no specific symptoms beyond fatigue and weight loss. His appetite is reduced but he has no dysphagia. He is a lifelong non-smoker. What is the most appropriate next step in management?

A 41-year-old woman presents with a 15-week history of fatigue and 5kg weight loss. She reports heat intolerance and palpitations. Her grandmother had 'thyroid problems'. Examination shows pulse 96 bpm regular, BP 138/72 mmHg, fine tremor, and a smooth thyroid gland enlarged to twice normal size with an audible bruit. Blood tests show: TSH <0.01 mU/L, free T4 42 pmol/L, free T3 12.8 pmol/L. TSH receptor antibodies are strongly positive. What is the most important counselling point before initiating definitive treatment?

A 62-year-old man presents with an 11-week history of intermittent fevers up to 38.6°C, night sweats, and 7kg weight loss. He has a 35-year history of Crohn's disease managed with adalimumab. Examination shows temperature 38.2°C, no lymphadenopathy, chest clear, abdomen soft with no masses. Blood tests show: Hb 102 g/L, WCC 11.2 × 10⁹/L, neutrophils 8.4 × 10⁹/L, CRP 78 mg/L. Chest X-ray is normal. Three sets of blood cultures are negative. What is the most appropriate next investigation?