Use of captopril in the diagnostic work-up of renovascular hypertension.

A total of 179 patients were selected for a diagnostic work-up of renovascular hypertension from a consecutive series of hypertensive patients referred to a single outpatient clinic between January 1978 and January 1985. Selection criteria were: (1) diagnostic blood pressure > 120 mmHg in patients of 40 years or younger, irrespective of whether they were on treatment or not, and/or (2) diastolic blood pressure > 100 mmHg despite combination therapy with at least three drugs. All patients underwent renal angiography. The diagnostic value of the responses of blood pressure and plasma renin 1 h after 50 mg captopril was assessed while the patients were untreated for at least 2 weeks. The captopril test had a predictive value of 0.92 using a concentration of enzymatically active renin in plasma > 200 microU/ml as criterion for a positive test. The predictive value of a negative test was 0.81. Predictive values were not improved by combining blood pressure response with renin level after captopril. The prevalence of renal artery stenosis was 50% (unilateral stenosis 34%). In a hypertension clinic where patients with severe or therapy-resistant hypertension and a high prevalence of renal artery stenosis are seen, the captopril test proves to be useful for selecting cases for renal angiography.