FRI132 Aldosterone Secretory Capacity Immediately After Surgery Predicts Biochemical Outcome 1 Year After Surgery In Primary Aldosteronism

Disclosure: Y. Ishida: None. K. Nakai: None. Y. Tsurutani: None. K. Watanabe: None. J. Saito: None. T. Nishikawa: None. Background and Objective: In primary aldosteronism (PA), the biochemical outcome of the Primary Aldosteronism Surgical Outcome (PASO) study is used to assess aldosterone hypersecretion six months to one year after surgery. However, there are few reports on whether outcomes can be predicted in the early postoperative period. This retrospective study evaluated aldosterone secretory capacity immediately after surgery using the adrenocorticotropin (ACTH) stimulation test (AST) and oral salt loading test (OST). We hypothesized that these tests would predict biochemical outcomes one year after surgery. Methods: This study assessed 282 patients with PA who underwent adrenalectomy in our hospital between 2008 and 2020 and determined biochemical PASO outcomes 1 year after surgery. Patients with serum cortisol levels ≥ 5 μg/dL after a 1 mg overnight dexamethasone suppression test (n = 9) were excluded. Patients were divided into biochemical complete success (COM) and incomplete (partial + absent) success (INC) groups. AST and OST were performed within 15 days of surgery. The relationships between various AST and OST values and outcomes were analyzed. Results: Two hundred and twenty patients and 53 patients were classified into the COM and INC groups, respectively. The INC group had significantly higher plasma aldosterone concentration (PAC) and higher PAC/cortisol ratio (A/C) at baseline, 30 min, and 60 min after ACTH loading than the COM group. The INC group showed a significantly lower level of plasma renin activity. In the OST, the INC group had a significantly higher 24-hour urine aldosterone level. Of these values, A/C at 30 minutes after ACTH loading (area under the curve (AUC) = 0.77) and 24-hour urine aldosterone (AUC = 0.78) were relatively superior predictors of the outcome, with higher AUCs than plasma renin activity (AUC = 0.63), baseline PAC (AUC = 0.71), baseline ARR (AUC = 0.72), and baseline A/C (AUC = 0.70). A/C at 30 minutes after ACTH loading had 83% sensitivity and 62% specificity when 6.03 was set as the cutoff; 24-hour urine aldosterone had 84% sensitivity and 61% specificity when 2.6 was set as the cutoff. Conclusion: AST and OST immediately after surgery are useful for predicting biochemical outcomes 1 year after surgery in patients with PA. Presentation: Friday, June 16, 2023