Q: What is Captopril Test ?

A; It is a simple poor man's test to diagnose renal cause for hypertension. It has high sensitivity but a low specificity.

In this test, the baseline level of renin in the blood is determined by drawing blood. Then an oral dose of captopril is given and, after an hour, the plasma renin level is determined again. Because captopril blocks the activity of one of the proteins that renin works on, the blood pressure should fall. This decrease in blood pressure is detected by both kidneys, but especially by the one that has a blocked blood supply. This kidney responds by secreting a large amount of renin. Thus an exaggerated renin response after the dose of captopril is suggestive of a renovascular hypertension. hypertension.



The captopril test for identifying renovascular disease in hypertensive patients. - Am J Med. 1986 Apr;80(4):633-44.