A male nephrotic patient with rapid decline of renal function

A 56-year-old African American male presented to the emergency room after 2 weeks of gradually worsening dyspnoea, cough, periorbital and lower extremity oedema, a 20 lb weight gain and dark coloured urine. The patient had a history of hypertension and hypercholesterolaemia, and had been treated with hydrochlorothiazide, lisinopril and atorvastatin. Three months previously, his blood urea nitrogen (BUN) was 22mg/dl (7.8mmol/l), serum creatinine was 1.3mg/dl (115 mmol/l) and urinalysis showed 3þ proteinuria by dipstick. Currently, his physical examination revealed a blood pressure of 177/125mmHg and periorbital and 3þ lower extremity oedema. Initial abnormal laboratory data included BUN of 47mg/dl, seru