Provocative captopril testing in the diagnosis of renovascular hypertension.

Firm recommendations concerning the testing procedures, radionuclides of choice, and diagnostic criteria for RVHT are somewhat difficult, given the lack of rigorous standardization of these complex protocols. Nevertheless, review of the existing data indicates that post-captopril renography alone appears to be a safe and effective means of noninvasively screening hypertensive patients for renovascular disease. A normal study after captopril suggests with a reasonable degree of certainty that potentially reversible RVHT is unlikely. A positive study in an appropriately screened hypertensive patient with preserved renal function suggests that renovascular disease is likely, with sensitivity and specificity in excess of 90%. In the comparative study of Elliott et al, captopril renography was a more sensitive and specific screening test than the captopril PRA test. Although there may be confounding variables such as renal dysfunction, medications, and types of stenosis, a positive captopril renogram might also suggest a cure or improvement in blood pressure control with successful intervention such as PTRA or revascularization. Whether captopril renography might predict stabilization of individual kidney function is speculative and deserves further study.