Basal and Post-ACTH Aldosterone and Its Ratios Are Useful During Adrenal Vein Sampling in Primary Aldosteronism

Context: Adrenal vein sampling (AVS) is required to identify a lateralized or bilateral aldosterone source in primary aldosteronism. Objectives: Our objectives were to compare basal and post-ACTH selectivity ratio (SR) and lateralization ratio (LR) and to determine the prevalence of basal contralateral suppression and its effect on surgical outcome. Patients and Intervention: Bilateral simultaneous adrenal vein samples were obtained before and after a 250-mu g bolus of ACTH. Analyses were conducted on 171 technically successful AVS and on the subgroup of 66 operated patients with evaluable outcome data. Results: ACTH increased selectivity on both sides from 66.7% in basal samples (SR >= 2) to 91.8% poststimulation (SR >= 5). A discordance of lateralization between basal (LR >= 2) and post-ACTH (LR >= 4) values was observed in 28% of cases, which were mostly lateralized cases basally that became bilateral post-ACTH. Basal CL suppression is present in only 30% using absolute ratio of aldosterone between the opposite (nondominant) adrenal vein and the peripheral vein A(OPP)/A(P) below 1.5 vs in 77% using aldosterone/cortisol ratio (A/C)(OPP)/(A/C)(P) below 1.5. The absence of CL suppression was associated with a lower rate of response to adrenalectomy in terms of clinical and biochemical parameters with difference in clinical cure (55% vs 13% P = .0003) and overall cure (35% vs 9%, P = .0084) using A(OPP)/A(P), but not when using (A/C)(OPP)/(A/C)(P). Conclusions: Stimulation with ACTH is useful to improve selectivity of AVS but can frequently modify interpretation of lateralization. Basal ratios are as important as post-ACTH ratios to set an indication of adrenalectomy. A(OPP)/A(P) is superior to (A/C)(OPP)/(A/C)(P) to assess contralateral suppression. Infrequent CL suppression reveals frequent occurrence of contralateral hyperplasia in lateralized cases and helps predict postoperative outcomes.