Basal contralateral aldosterone suppression is rare in lateralized primary aldosteronism

Unilateral aldosteronomas should suppress renin and contralateral aldosterone secretion. Complete aldosterone suppression in contralateral adrenal vein sample (AVS) could predict surgical outcomes.

To retrospectively evaluate the prevalence of basal contralateral suppression using Aldosterone (A)contralateral(CL)/Aperipheral(P) as compared to (A/Cortisol(C)CL)/(A/C)P ratio in primary aldosteronism (PA) patients studied in two Canadian centers. To determine the best cut-off to predict clinical and biochemical surgical cure. To compare the accuracy of ACL/AP to the basal and post-ACTH lateralization index (LI) in predicting surgical cure.

In total, 330 patients with PA and successful AVS were included; 124 lateralizing patients underwent surgery. Clinical and biochemical cure at 3 and 12 months were evaluated using the PASO criteria.

Using ACL/AP and (A/C)CL/(A/C)P at the cut-off of 1, the prevalence of contralateral suppression was 6 and 45%, respectively. Using ROC curves, the ACL/AP ratio is associated with clinical cure at 3 and 12 months and biochemical cure at 12 months. (A/C)CL/(A/C)P is associated with biochemical cure only. The cut-offs for ACL/AP offering the best sensitivity (Se) and specificity (Sp) for clinical and biochemical cures at 12 months are 2.15 (Se: 63% and Sp: 71%) and 6.15 (Se: 84% and Sp: 77%), respectively. Basal LI and post-ACTH LI are associated with clinical cure but only the post-ACTH LI is associated with biochemical cure.

In lateralized PA, basal contralateral suppression defined by ACL/AP is rare and incomplete compared to the (A/C)CL/(A/C)P ratio and is associated with clinical and biochemical postoperative outcome, but with modest accuracy.