SUN-249 - Reducing the Need for Adrenal Vein Sampling: Post-CCT Aldosterone as A Key Predictor

While unilateral primary aldosteronism (PA) is surgically curable, bilateral PA needs to be controlled with continuous pharmacological treatment. Thus, the lateralization of the PA lesion is crucial to treatment decisions and outcomes, and this can be assessed through adrenal vein sampling (AVS). We explored a noninvasive test to determine the cutoff for predicting surgically curable unilateral PA.
AVS was performed under adrenocorticotropic hormone stimulation in patients with suspected PA and post-saline infusion test (SIT) results demonstrating aldosterone levels above 5 ng/dL. We analyzed 29 patients with successfully inserted catheters (selectivity index >5) who underwent a captopril challenge test (CCT). During AVS, a lateralization index of 3 or below was considered bilateral, while 4 or higher was considered unilateral. The K+ levels, aldosterone-to-renin ratio (ARR), and post-SIT and post-CCT aldosterone levels were analyzed for the prediction of lateralization and its cutoff point using the receiver operating characteristic (ROC) curve.
There were no differences in baseline aldosterone, ARR, and post-SIT aldosterone levels between the bilateral and unilateral PA groups, but the unilateral group had significantly lower blood K+ (3.6±0.6 vs. 3.1±0.2 mEq/L; p=0.028) and significantly higher post-CCT aldosterone levels (12.6±6.2 vs. 16.6±3.8 ng/dL; p=0.028). In the ROC analysis to analyze the predictability of lateralization (unilateral PA), blood K+, baseline aldosterone, ARR, and post-SIT aldosterone levels were not significant. However, post-CCT aldosterone levels significantly predicted lateralization (area under curve=0.813; p=0.040), with a cutoff point of 15.6 ng/dL (sensitivity=0.800; specificity=0.800).
The CCT is a useful tool for predicting lateralization via AVS, and the optimal cutoff point for post-CCT aldosterone levels is 13.8 ng/dL. Thus, if post-CCT aldosterone levels are below 15.6 ng/dL, the possibility of surgically curable PA can be eliminated, making invasive AVS unnecessary.

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