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Response to the captopril test is dependent on baseline renin profile
L M Gerber1, S J Mann, F B Müller
1Cardiovascular Center, New York Hospital-Cornell Medical Center, NY 10021.
Journal of Hypertension
|February 1, 1994
Summary
An exaggerated renin response to captopril challenge is common in high-renin essential hypertension. Caution is advised when interpreting positive captopril test results in these patients, especially with a low probability of renovascular hypertension.
Area of Science:
- Cardiology
- Nephrology
- Endocrinology
Background:
- Essential hypertension is a complex condition with varying renin-angiotensin-aldosterone system (RAAS) activity.
- The renin-sodium profile helps categorize hypertensive patients based on their RAAS status.
- The captopril challenge test is used to assess renin responsiveness, but its interpretation can be influenced by baseline renin levels.
Purpose of the Study:
- To investigate the relationship between the renin-sodium profile and the renin response to captopril in patients with essential hypertension.
- To assess the diagnostic accuracy of the captopril test in identifying renovascular hypertension in different renin-sodium profile groups.
Main Methods:
- A prospective study involving 108 untreated hypertensive subjects with normal renal function and sodium excretion.
- Standard captopril challenge test performed, with positive results defined by specific criteria for plasma renin activity increase.
- Further investigation for renovascular hypertension using renal venous renins and digital subtraction angiography for selected patients.
Main Results:
- False-positive captopril test results were significantly more common in high-renin subjects (31%) compared to low/normal renin subjects (1%).
- The magnitude of renin response to captopril was directly correlated with baseline plasma renin activity.
- False-positive results were not associated with urinary sodium excretion or blood pressure changes.
Conclusions:
- An exaggerated renin response to captopril is frequent in high-renin essential hypertension.
- Interpreting a positive captopril test requires caution in patients with high baseline renin, particularly in populations with low prevalence of renovascular hypertension.