Severe hypertension in newborn after pyeloplasty of hydronephrotic kidney.

A case is described, believed to be the first reported, of a newborn in whom severe hyperreninemic hypertension developed after pyeloplasty of a hydronephrotic kidney. Management of the hypertension required large doses of antihypertensive agents, including sodium nitroprusside, for six postoperative days. Propranolol had to be given for eight months after surgery. The possibility that thiocyanate level in a newborn is unreliable as indicator of sodium nitroprusside overdosage is considered.