title: A prospective evaluation of a simplified captopril test for the detection of renovascular hypertension.
abstract: 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 (ngAl.mL-1.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 ngAl.mL-1.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 ngAl.mL-1.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.
authors.affiliation: Department of Medicine, University of Florida, Gainesville.
authors.forename: E D
authors.initials: ED
authors.lastname: Frederickson
authors.forename: C S
authors.initials: CS
authors.lastname: Wilcox
authors.forename: M
authors.initials: M
authors.lastname: Bucci
authors.forename: N R
authors.initials: NR
authors.lastname: Loon
authors.forename: J C
authors.initials: JC
authors.lastname: Peterson
authors.forename: N L
authors.initials: NL
authors.lastname: Brown
authors.forename: R D
authors.initials: RD
authors.lastname: Thompson
authors.forename: T B
authors.initials: TB
authors.lastname: Smith
authors.forename: C S
authors.initials: CS
authors.lastname: Wingo
mesh_terms: D002216:Captopril; D004232:Diuretics / Q000627:therapeutic use; D006801:Humans; D006973:Hypertension / Q000175:diagnosis; D006978:Hypertension, Renovascular / Q000175:diagnosis* / Q000453:epidemiology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012083:Renin / Q000097:blood; D012680:Sensitivity and Specificity
chemical_list: D004232:Diuretics; D002216:Captopril; D012083:Renin