FRI148 Adrenal Vein Sampling: Intra-protocol Hormonal Variability

Disclosure: C. Lee: None. Z. Salman: None. J. Shields: None. A.F. Turcu: None. Background: Primary aldosteronism (PA) might arise from one or both adrenal glands. Treatment of PA relies on determining the relative contribution of aldosterone from the two adrenal glands. Adrenal vein sampling (AVS) is essential to identifying patients with lateralized PA (LPA), who benefit from surgery. AVS procedure and interpretation protocols differ between centers. Variability in AVS lateralization has been primarily attributed to cosyntropin use and lateralization index (LI) thresholds. However, data on intra-protocol variability are lacking. Methods: We retrospectively reviewed the clinical records of patients with PA who underwent AVS at University of Michigan between January 2015 and December 2022. In our center, AVS is performed both before and after cosyntropin stimulation, and 6 sets of paired adrenal vein and peripheral serum are obtained: 3 at baseline, and 3 between 5-30 min after cosyntropin stimulation. We included patients who had successful adrenal vein catheterization and valid data from 6 time points. A LI≥4 was considered indicative of LPA. We assessed the rates of inconsistent AVS results within baseline and cosyntropin stimulated samples as proportion of sets in which 1/3 LIs provided different subtyping results than the other 2/3. Results: Of 361 patients included, 107 (29.6%) patients had at least one inconsistent LI. Of these, 74 (20%) patients had an inconsistent LI within the basal sets, 45 (12%) within the cosyntropin stimulated sets, and 12 (3.3%) patients had a discrepant result in both baseline and cosyntropin stimulated sets. The highest outlier rates were observed in the first basal sample (30.3%), followed by the third basal sample (21.9%), the first post-cosyntropin sample (16.0%), and the last post-cosyntropin sample (13.5%). Patients with one intra-protocol outlier were younger (mean age 52.2 ± 11.5 vs. 56.2 ± 10.8 years), but there were no sex, race distribution, or BMI differences between the two groups. Conclusions: The intra-procedural AVS data variability is almost twice as high in basal vs. post-cosyntropin stimulation sampling, particularly in the initial set, likely mediated by acute ACTH fluctuations during the procedure. Our results emphasize the importance of obtaining multiple AVS data sets, in order to best inform the decision for or against surgery. Presentation: Friday, June 16, 2023