How is the captopril test performed in the workup of hyperaldosteronism?

Updated: Oct 19, 2018
  • Author: George P Chrousos, MD, FAAP, MACP, MACE, FRCP(London); Chief Editor: Robert P Hoffman, MD  more...
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The captopril test has also been used for screening. Its use is based on the principle that inhibition of angiotensin II production should not affect autonomous secretion of aldosterone in PA. Patients receive 25–50 mg of oral captopril after sitting or standing for 1 h. Plasma aldosterone concentration, renin, and cortisol levels are measured before captopril administration and 1 or 2 hours after. Plasma aldosterone concentration is suppressed by 30% or more if primary hyperaldosteronism is not present. ARR is more than 30–50, plasma aldosterone concentration remains elevated (≥8.5 ng/dL), and renin remains suppressed in primary hyperaldosteronism. Differences may be seen between patients with APA and those with IHA, in that some decrease of aldosterone levels is occasionally seen in IHA. High rates of false negative or equivocal results have been reported, although this test is considered safer in patients at risk of volume overload.

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