Special uses for captopril.

Plasma renin activity (PRA) is markedly increased by captopril. There is not enough separation between the changes in PRA of patients with renal artery stenosis (RAS) to separate them reliably from those with essential hypertension. A minimal response may suggest primary aldosteronism. Captopril does increase the ratio of PRA in the venous blood from a kidney with RAS to that of the contralateral kidney. Captopril, 25 to 50 mg orally, given before renal vein PRA sampling will increase the sensitivity and specificity of the test. Treatment with current antihypertensive drugs need not be discontinued. Scleroderma renal crisis (SRC) used to be uniformly lethal within a few months. Modern, aggressive antihypertensive therapy has made survival of 2 or more years common. Not all patients respond, and some progress to renal failure despite good BP control. Captopril has been used with success in some patients with idiopathic edema. In conclusion, captopril markedly enhances the accuracy of renal vein renin assay for the diagnosis of RAS and is of major value in the treatment of SRC.