MON-286 Aldosterone-to-Potassium Ratio for Predicting Lateralized Primary Aldosteronism in Patients with Unilateral Adrenal Nodules

Abstract Disclosure: P. Vibhatavata: None. W. Watanakitsiri: None. Background: Adrenal venous sampling (AVS) is the current standard for subtyping primary aldosteronism (PA), but its utility is limited by experienced interventionists and the risk of catheterization failure. Markedly high aldosterone levels, severe hypokalemia, and adrenal nodules on imaging may help guide subtyping when AVS is unavailable. This study evaluates the aldosterone-to-potassium ratio (APR) for predict lateralized PA in patients with unilateral adrenal nodules. Methods: This retrospective study included PA patients with unilateral adrenal nodules and successful AVS between January 2012 and December 2024. The APR was compared between lateralized and bilateral PA, and its diagnostic cut-off for lateralized PA was determined. Results: Among 85 patients, median age was 56 years, and 53% were men. Median potassium and aldosterone levels were 2.9 mmol/L and 26 ng/dL, respectively. Fifty-one patients (60%) had lateralized PA, while 34 (40%) had bilateral PA. Median APR was significantly higher in lateralized PA compared to bilateral PA (12.4 vs 6.2 ng/dL: mmol/L, p<0.01). The APR threshold of 12 ng/dL: mmol/L, determined by ROC analysis, predicted lateralized PA with an AUC of 0.796 (p<0.001), achieving 57% sensitivity and 91% specificity. Conclusion: The APR shows potential as a practical tool for predicting lateralized PA in patients with unilateral adrenal nodules. Its diagnostic performance supports its use as a supplementary approach for subtyping when AVS is unavailable. Key Words: adrenal nodule, aldosterone, potassium, primary aldosteronism, adrenal vein sampling Presentation: Monday, July 14, 2025