Intraprotocol Adrenal Vein Sampling Inconsistencies in Primary Aldosteronism Lateralization.

Background Primary aldosteronism can arise from one or both adrenal glands. Adrenal vein sampling (AVS) is the standard of care for identifying patients with lateralized primary aldosteronism who would benefit from surgery. Variability in AVS lateralization has been primarily attributed to cosyntropin use and lateralization index thresholds. Data regarding intraprotocol variability are lacking. Purpose To assess the rates of intraprotocol lateralization inconsistency during simultaneous AVS. Materials and Methods This retrospective cross-sectional study assessed patients with primary aldosteronism who underwent simultaneous AVS at a single tertiary referral center between January 2015 and December 2023. Six sets of adrenal vein and peripheral vein samples were obtained: three baseline samples obtained after cannulation, 5 minutes apart; and three samples obtained between 5 and 30 minutes after cosyntropin stimulation. Patients with successful cannulation and valid hormonal data at all six time points were included. A lateralization index (computed as the aldosterone-to-cortisol ratio between the two adrenal veins, with the highest number as numerator) of at least 4 was considered indicative of lateralized primary aldosteronism. The proportions of baseline and stimulated AVS sets within which one of three lateralization indexes provided different subtype results were assessed. Linear mixed-effects models were used to estimate the between- and within-patient hormonal and lateralization index variances. Results Of 402 patients (median age, 53 years; IQR, 45-63 years; 233 male) included, 129 patients (32.1%) had at least one lateralization index inconsistency. Of these 402 patients, 89 patients (22.1%) had lateralization inconsistencies within the baseline sets, 53 patients (13.2%) within cosyntropin-stimulated sets, and 13 patients (3.2%) in both baseline and cosyntropin-stimulated sets. The highest outlier prevalence occurred in the first (42 patients; 10.4%) and third (33 patients; 8.2%) baseline samples, with roughly twofold-lower rates in the first (23 patients; 5.7%) and last postcosyntropin stimulation samples (4.2%; 17 patients). The absolute change in baseline and cosyntropin-stimulated lateralization index (maximum-minimum lateralization index within a triplicate) was as high as 152.9 and 327.4, respectively. The highest hormonal variability was noted in the adrenal vein producing less aldosterone. Conclusion Almost a third of patients undergoing AVS in triplicate, both before and after cosyntropin stimulation, had intraprotocol discrepancies in lateralization results, with the highest variability occurring within samples obtained without cosyntropin stimulation. © RSNA, 2025 See also the editorial by Georgiades in this issue.