MON-299 Multicomponent Lateralization Index to Enhance the Accuracy of Adrenal Venous Sampling (AVS) in Primary Aldosteronism Subtyping

Abstract Disclosure: Y. Marcus-Perlman: None. G. Shefer: None. I. Kori: None. M. Ingbir: None. Y. Greenman: None. N. Stern: None. AVS is crucial for diagnosing primary aldosteronism (PA), relying on cortisol-based selectivity and lateralization indices (SI/LI). However, variability in cortisol levels and aldosterone-cortisol co-secretion can hinder diagnostic accuracy. A multicomponent lateralization index incorporating 17-hydroxyprogesterone (17OHP) and the contralateral suppression index (CSI) may improve subtype differentiation between aldosterone-producing adenoma (APA) and bilateral hyperaldosteronism (BHA). In this study, AVS without cosyntropin stimulation was conducted on 27 patients, with 25 successful procedures (14 APA, 11 BHA). Clinical and laboratory data highlighted key differences: APA patients exhibited lower plasma renin activity (0.06 ± 0.04 vs. 0.17 ± 0.13ng/ml/min) and higher aldosterone concentration (38 ± 20 vs. 25 ± 10.3 ng/dL) than BHA patients. APA patients also showed elevated aldosterone-to-cortisol (19.7 ± 14.2 vs. 1.9 ± 0.5), aldosterone-to-17OHP (35.3 ± 44 vs. 4.5 ± 5.2), and aldosterone-to-DHEAS ratios (26.7 ± 33.9 vs. 2.63 ± 1.7). Metabolic abnormalities, including diabetes (3 cases) and impaired fasting glucose (7 cases), and abnormal 1mg dexamethasone suppression test (1 case) were more prevalent in APA than in BHA (1 and 2 cases, respectively). Surgical intervention was performed in 12 APA patients, compared to 1 in the BHA group. We suggest a multicomponent index that improves the interpretation of AVS when LI values are borderline. Index includes cortisol-corrected LI (cutoff>4), 17OHP LI (cutoff>5), and CSI (≤0.5 for cortisol or 17OHP-corrected CSI<3). For example, in a suspected APA case with borderline cortisol LI (2.96), the addition of aldosterone/17OHP LI (>5) and CSI (<0.5) solidified the diagnosis which was then confirmed by surgical cure. Conversely, reliance on marginally positive lateralization such as cortisol LI (4.01) and 17OHP LI (5.14) was offset by high CSI >4 which correctly predicted poor postoperative outcomes. Notably, indices derived from DHEA-S were not helpful in refining diagnoses. These findings highlight the advantage of integrating 17OHP-derived LI and CSI into AVS analyses to enhance diagnostic precision for PA subtyping. Further studies are needed to establish refined cutoff values and to facilitate routine use of 17OHP in clinical practice. Presentation: Monday, July 14, 2025