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March 1990

A Prospective Evaluation of a Simplified Captopril Test for the Detection of Renovascular Hypertension

Author Affiliations

From the Division of Nephrology, Hypertension, and Transplantation, Department of Medicine, University of Florida (Drs Frederickson, Loon, and Peterson and Ms Brown and Mr Thompson); Veterans Administration Medical Center (Drs Wilcox, Smith, and Wingo and Mr Bucci), Gainesville. Dr Frederickson is with Emory University, Atlanta, Ga. Dr Loon is with Stanford University, Palo Alto, Calif. Dr Smith is with the University of South Florida, Tampa.

Arch Intern Med. 1990;150(3):569-572. doi:10.1001/archinte.1990.00390150065013

• Renovascular hypertension is potentially curable but of low prevalence. A previous retrospective study has demonstrated the use of a potentiated increase in plasma renin activity after captopril administration as a diagnostic test for renovascular hypertension; this requires two blood samples for plasma renin activity determination and three inclusive criteria for a positive test result. We applied this test prospectively to screen 100 hypertensive patients for renovascular hypertension. We evaluated 29 patients with renovascular hypertension; the remainder were diagnosed as having essential hypertension. In our patient population, a postcaptopril plasma renin activity of 5.7 ng of angiotensin per milliliter per hour (ngAI·mL1·h−1) or greater had a 100% sensitivity and an 80% specificity for renovascular hypertension. An absolute increase in plasma renin activity with captopril of 4.7 ngAI·mL1·h−1 or greater had a lower sensitivity of 90% and a specificity of 87%, whereas a fractional increase in plasma renin activity after captopril of 150% or higher had the lowest sensitivity of 69% and a specificity of 86%. A subgroup analysis of 38 patients who were receiving diuretic therapy demonstrated that the test sensitivity was unchanged but the specificity was reduced. In conclusion, a single postcaptopril plasma renin activity value of 5.7 ngAI·mL1·h−1 or greater is a simplified screening test for renovascular hypertension, with excellent sensitivity and acceptable specificity. This test is well tolerated, inexpensive, and easy to perform.

(Arch Intern Med. 1990;150:569-572)

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