Congenital hypertension due to unilateral renal vein thrombosis.

A boy was found on the day of birth to have hypertension and radiological evidence of calcification of the left renal vein. Persistent hypokalaemia and hyper-reninaemia in the presence of a small left kidney and normal right kidney led to the decision to perform a left nephrectomy. The biopsied specimen showed old calcified renal vein thrombosis with accompanying medullary necrosis. Postoperatively hypertension resolved.