Abstract P100: Paradoxical Increase In Post-Captopril Aldosterone

Abstract

Hypertension remains one of the strongest risk factors for cardiovascular disease. Primary aldosteronism, the most common form of secondary hypertension, can be confirmed using the captopril challenge test. This study aims to investigate a subset of patients who exhibit a paradoxical increase in aldosterone levels after the administration of captopril, despite the expected decrease in aldosterone production. A retrospective design was employed to evaluate patients who exhibited atypical captopril suppression test results. The cohort consisted of 120 patients who underwent the captopril suppression test as part of their diagnostic evaluation for resistant hypertension. Demographic data and clinical parameters were collected for each patient.Among the patients who tested positive on the captopril suppression test based on a post-aldosterone level criterion of >12 mg/dL, one-third exhibited an increase equal to or greater than 50% in aldosterone levels (9 out of 27).We proposed different theories to explain this phenomenon. Intraindividual variability, which has been previously reported with a laboratory coefficient of variation between 2.7% and 4.4%, was ruled out using a cut-off ≥ 50%. Another possibility is the presence of extraadrenal aldosterone production independent of the regulation provided by captopril or ATII. This could be attributed to unrecognized compensation of aldosterone production by extra-adrenal tissues in response to a decrease in adrenal aldosterone levels. Additionally, conditions such as preeclampsia, post-transplant acute rejection, autoimmune diseases, lupus, and primary hyperaldosteronism have been associated with increased aldosterone production by zona glomerulosa cells due to the presence of activating antibodies.There are certain limitations to this study. Other biochemical tests were not performed, and the sample size was relatively small, making it challenging to draw definitive conclusions. In conclusion, this study aims to contribute to our understanding of the pathogenesis of primary aldosteronism. The findings highlight the utility of the captopril suppression test as a biochemical confirmation test for the diagnosis of primary aldosteronism and resistant hypertension.