ACTH stimulation and oral salt loading tests detect biochemical outcome early after primary aldosteronism surgery

Background: In primary aldosteronism (PA), the biochemical outcomes of the Primary Aldosteronism Surgical Outcome study are used to assess aldosterone hypersecretion 6-12 months after surgery. However, few studies have investigated whether the outcomes can be predicted in the early postoperative period. In this retrospective study, we evaluated whether the adrenocorticotropin stimulation test (AST) and oral salt loading test (OST) performed immediately after surgery could predict biochemical outcomes 1 year after surgery.

Methods: We assessed 268 patients with PA who underwent adrenalectomy at our hospital between 2008 and 2020, underwent AST and OST within 15 days of surgery, and were assessed for biochemical outcomes 1 year after surgery. Patients were divided into two groups: biochemical complete success (B-com; n = 219) and incomplete success (B-inc; n = 49). Patients were divided into clinical complete and partial success and absent success groups. The relationships between various AST and OST values and outcomes were analyzed.

Results: The B-inc group had significantly higher plasma aldosterone concentration (PAC) and PAC/serum cortisol ratio (PAC/Cort) at baseline and after ACTH loading in AST and 24-hour urine aldosterone in OST than the B-com group. PAC/Cort at 30 min after ACTH loading (area under the curve (AUC) = 0.76) and 24-hour urine aldosterone (AUC = 0.77) were relatively superior predictors of the outcome. Parameters after ACTH loading were better predictors of biochemical and clinical outcomes than baseline.

Conclusions: AST and OST immediately after surgery can predict biochemical and clinical outcomes 1 year after surgery in patients with PA.