A man with thrombocytopenia

A 70 year old Nigerian man presented to an emergency department in west London with a two day history of progressive drowsiness, lethargy, and reduced appetite. He had no history of fever, cough, urinary symptoms, gastrointestinal symptoms, headaches, or focal neurology. He had a history of type 2 diabetes treated with metformin and glibenclamide, no known allergies, and was fully independent with his activities of daily living. Although he lived in the United Kingdom, he travelled to Nigeria two to three times a year. His last visit to Nigeria had been two months earlier. He had never smoked and rarely drank alcohol.

On examination, he did not have a fever (36.7°C), his blood pressure was 113/70 mm Hg, and heart rate was 100 beats/min. He was drowsy but could be roused and had a Glasgow coma scale score of 14. Systems examinations were normal.

The bedside blood glucose concentration was 20.6 mmol/L (reference range 3.9-7.8). His urine dipstick was positive for blood and protein. His venous blood gases showed a pH of 7.38 kPa (7.35-7.45), bicarbonate 22 mmol/l (22-26), base deficit −3.3 (−2 to +2), and lactate 2.7 mmol/L (0.5-2). Blood tests showed white cell count 7.2×10⁹/L (4-11), haemoglobin 125 g/L (125-170), platelet count 21×10⁹/L (120-400), activated partial thromboplastin time 28.5 s (24-32), prothrombin time 10.9 s (9.6-11.6), and international normalised ratio 1.2. The C reactive protein was 214 mg/L (0-10), urea 13.8 mmol/L (2.5-8), creatinine 107 mmol/L (60-125), sodium 129 mmol/L (135-145), potassium 4.4 mmol/L (3.5-5.3), total bilirubin 48 μmol/L (0-17), alanine aminotransferase 28 IU/L (0-40), alkaline phosphatase 77 IU/L (30-130), and albumin 27 g/L (33-47).

Electrocardiography showed sinus tachycardia. Chest radiography showed clear lung fields. In view of the thrombocytopenia a blood film was requested (figs 1⇓ and …