Comparison of rapid ACTH stimulation test and the captopril challenge test in PA

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 723-757-Renin-Angiotensin-Aldosterone System/Endocrine Hypertension
Bench to Bedside
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-732
Aya Tsumagari*1, Kazutaka Nanba1, Mika Tsuiki1, Kanako Nakao1, Youhei Ueda1, Maiko Kakita1, Rieko Nakatani1, Tetsuya Tagami1, Takeshi Usui1, Akira Shimatsu1, Akiyo Tanabe2 and Mitsuhide Naruse1
1National Hospital Organization Kyoto Medical Center, Kyoto, Japan, 2Tokyo Women's Medical University, Tokyo, Japan
Objective: Confirmatory testing is a diagnostic step to prove autonomous and excess aldosterone secretion in PA. Although several tests have been used as a confirmatory testing, the rapid ACTH stimulation test (ACTH-T) is the only test to demonstrate hyperresponsibility to ACTH. The aim of the study was to investigate the difference of clinical significance of ACTH-T and captopril challenge test (CAP-T).

Patients and Methods: The study included 193 hypertensive patients with positive screening test of PA (ARR>200). 83 patients were diagnosed as PA based upon the results of adrenal venous sampling, adrenal scintigraphy, and/or pathological findings after surgery. Patients were divided into groups based upon the results of ACTH-T and CAP-T, and various clinical presentations were compared between the groups.

Results: In 193 hypertensive patients with positive ARR, 144 patients showed positive results both in ACTH-T and CAP-T (A (+) C (+)), 27 patients showed positive results only in ACTH-T (A (+) C (-)), and 22 patients showed positive results only in CAP-T (A (-) C (+)). 49 patients showed discrepancy between ACTH-T and CAP-T. PAC, urinary excretion of aldosterone (u-aldo), and the incidence of hypokalemia were significantly higher in the A (+) C (-) group than in the A (-) C (+) group. On the other hand, PRA was significantly lower and ARR was significantly higher in the A (-) C (+) group than in the A (+) C (-) group. In 83 patients with confirmed diagnosis of PA, 74 patients were in the A(+)C(+) group, 4 patients were in the A(+)C(-) group, and 5 patients were in the A(-)C(+) group. 9 patients showed discrepancy between ACTH-T and CAP-T. In the A (+) C (-) group, PAC and u-aldo were significantly higher than in the A (-) C (+) group, but there was no significant difference in PRA and ARR between the groups. In the A (+) C (-) group, 1 of 4 patients was unilateral, and 2 patients showed hypokalemia. In the A (-) C (+) group, 2 of 5 patients were unilateral, and no patients showed hypokalemia. There was no significant difference in the adrenal tumor size between the groups.

Conclusion: The present results suggested that ACTH-T reflected more the extent of excessive aldosterone, while CAP-T reflected more the degree of renin suppression. Given the different endocrinological nature of the tests as well as the presence of patients with discrepant results, it could be recommended to carry out both tests as a confirmatory testings of PA.

Nothing to Disclose: AT, KN, MT, KN, YU, MK, RN, TT, TU, AS, AT, MN

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