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-μg 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 AOPP/AP 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 AOPP/AP, 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. AOPP/AP 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.