• pneumonia
• hematuria
• glomerulonephritis

A 5-year-old boy presented with 2 days of fever and cough. On examination, he had mild dyspnoea and chest pain, with crackles and hypoventilation at the right lung base. Blood tests showed white blood cells of 39.1×109/L, neutrophils of 28.9×109/L, haemoglobin of 11.3 g/dL, platelets of 375×109/L, c-reactive protein of 28.7 mg/dL and  erythrocyte sedimentation rate of 41 mm/hour. Chest X-ray confirmed a pulmonary consolidation in the right lower lobe (figure 1), with an associated pleural effusion. Bacterial pneumonia was diagnosed and intravenous ceftriaxone 100 mg/kg/ day was started. The following day, he developed palpebral oedema and his urine became tea-coloured. His blood pressure was 126/82 mm Hg (>99th percentile).1 Serum creatinine rose from 0.45 mg/dL to 1.09 mg/dL (39.8–93.4 µmol/L) and C3 was 9 mg/dL (normal range 90–180 mg/dL). Urinalysis revealed gross haematuria and 3+ proteinuria, with microscopy showing dysmorphic red blood cells with casts. Ultrasounds showed enlarged …