A case of hyperreninemic hypertension with unilateral hydronephrosis

A patient with unilateral ureteral obstruction by urolithiasis at the ureteropelvic junction was accompanied by hypertension. Plasma renin activity (PRA) was high in peripheral veins and was significantly higher in the renal vein drained from the affected kidney than the contralateral. Infusion of angiotensin II antagonist or an oral administration of captopril, an angiotensin converting enzyme (ACE) inhibitor, resulted in a prompt drop of blood pressure. After pyelolithotomy was successfully performed, both the blood pressure and peripheral PRA completely normalized. It is suggested that the renin-angiotensin system might have played a major role in the mechanism of the accompanied hypertension. Hyperreninemia could have been caused by both renal ischemic vasoconstriction, which might be due to uretero-renal reflex, and increased synthesis of prostaglandins resulting from ureteropelvic obstruction.