An 87 year old woman presented with breathlessness, which was worse on exertion and when she was lying flat. She had a longstanding history of hypertension, hypercholesterolaemia, and cigarette smoking. She had been referred to a nephrologist two years earlier and was found to have a creatinine of 270 μmol/L, with 2+ proteinuria on urine dipstick, a normal albumin (45 g/L), and no oedema. She was lost to follow-up before investigations were complete. On re-presentation, she described new shoulder and lower back pain. Her pulse was 80 beats/min and regular, blood pressure was 130/60 mm Hg, and jugular venous pressure was raised with bibasal inspiratory crepitations and peripheral oedema. Urine dipstick showed 3+ proteinuria and a trace of blood (recent protein:creatinine ratio 850 mg/mmol; reference value <15 mg/mmol). Her urea was 35 mmol/L (2.5-6.7), creatinine 357 μmol/L (54-145), albumin 32 g/L (35-50), haemoglobin 80 g/L (120-150; normocytic picture), and kidney bipolar length was 10 cm on both sides. Serum and urine protein electrophoresis was performed and immunoglobulins, antineutrophil cytoplasmic antibodies, antineutrophil antibodies, and complement components were measured. After a week of diuretics her urea and creatinine increased to 53 mmol/L and 601 μmol/L, respectively, with ongoing oedema. She started haemodialysis. A chest radiograph obtained at re-presentation is shown in fig 1⇓.