SAT-063 Peripheral Aldosterone Values During Simultaneous Bilateral Adrenal Veins Sampling (AVS) to Predict the Source of Aldosterone Secretion in Primary Aldosteronism (PA)

Background: AVS identifies aldosterone source in PA from unilateral aldosterone-producing adenoma (APA) or bilateral adrenal hyperplasia (BAH). APA and BAH can overexpress ACTH receptors, but their variable levels may explain discordant lateralization results between basal and post ACTH values (1,2). Previous studies suggested that differential response of plasma aldosterone concentration (PAC) to ACTH stimulation could predict the subtypes of PA (3). Objective: Assess the usefulness of peripheral (P) vein PAC response to ACTH to differentiate the source of excess aldosterone in patients with PA. Methods: In 215 bilaterally selective simultaneous AVS, PAC and plasma cortisol (C) were measured basally (-5 , 0 min,) and 5, 10, 15 min following ACTH 250 mcg IV bolus in adrenal and P veins; samples were also measured in P at 30, 45 and 60 min. Patients were assigned to four different lateralization ratio (LR) groups: group 1 (n= 140) lateralized source (basal LR ≥ 2 and post-ACTH LR ≥ 4), group 2 (n= 38) basal lateralization only (basal LR ≥ 2 and post-ACTH < 4), group 3 (n=10) post ACTH lateralization only (basal LR < 2 and post-ACTH ≥ 4) and group 4 (n= 27) bilateral source (basal LR < 2 and post-ACTH < 4. The P vein parameters included: mean basal PAC, maximal PAC (PAC(max)) and maximal PAC/C ratio (PAC(max)/C) following ACTH bolus, PAC absolute increase, PAC relative increase, maximal absolute variation of PAC/C ratio between post-ACTH and basal measures. Results: Mean basal PAC in P was significantly higher in group 1 than in group 2 or 4 (p < 0.001). PAC(max), PAC(max)/C and PAC absolute increase following ACTH bolus were higher in group 1 than the others (p < 0.017). Group 4 had higher PAC relative increase following ACTH bolus than group 1 (p: 0.0097). ROC curves analysis for these parameters were performed by comparing group 1 with the others. Best AUC were obtained with mean basal PAC (AUC: 0.7386 95% IC: 0.67-0.81), PAC(max) (AUC: 0.7386 95% IC: 0.67-0.81) and PAC(max)/C (AUC: 0.7546 95% IC: 0.68-0.82). A mean basal P vein PAC of 678 pmol/L provides a specificity of 91% and a sensitivity of 41%, PAC(max)/C of 3.63 provides a specificity of 91% and a sensitivity of 43%, while a PACmax of 2128 pmol/L provides a specificity of 91% and a sensitivity of 47% to exclude cases of bilateral disease. Conclusion: P mean basal PAC and PAC(max) and PAC(max)/C following ACTH are higher in basal and ACTH lateralized PA than in the other groups. BAH patients have a higher relative increase in P PAC than basal and post-ACTH lateralized PA. The selected P PAC cutoff values fail to adequately distinguish all groups and cannot replace the requirement to conduct AVS. References: (1) El Ghorayeb et al., J Clin Endocrinol Metab. 2018;101:1826-1835. (2) Zwermann et al., Eur J Endocrinol. 2009;160 (3):443-451 (3) Jiang et al., J Clin Endocrinol Metab. 2015;100(5):1837–44.