12383 Salivary Cortisone Measurement In Mild Autonomous Cortisol Secretion: Retrospective Single-center Cohort Study

Abstract Disclosure: C.A. Villavicencio Torres: None. Y. Chai: None. S.K. Grebe: None. T.D. Maus: None. I. Bancos: None. Background: Mild autonomous cortisol secretion (MACS) is diagnosed based on abnormal post-dexamethasone cortisol >1.8 mcg/dL. Late-night salivary cortisol (SalF) measurements in MACS are usually within normal ranges, and as such are not recommended by the adrenal incidentaloma guidelines. Late-night salivary cortisone (SalE) measurement may have a higher accuracy than SalF in diagnosing MACS. Objectives: To determine associations between SalF and SalE and post-dexamethasone cortisol concentrations in patients with MACS. Methods: We conducted a single-center retrospective cohort study of data between 2020-2023 that included patients with MACS who had concomitant SalF and SalE measurements at the time of diagnosis. Electronic medical records were reviewed for clinical, imaging, biochemical characteristics, and outcome data. Results: In 45 patients with MACS (31, 69% women) evaluated at a median age of 62 years (IQR 54-70), median post-dexamethasone cortisol was 3 mcg/dL (IQR 2.5-5.7), median corticotropin (ACTH) was 11 pg/mL (IQR 5.2-30), and median dehydroepiandrosterone sulfate (DHEAS) was 47.5 mcg/dL (IQR 27.8-98.8). In 36 patients, 24h-urine cortisol was also available, with a median cortisol of 14 mcg/dL (IQR 11.3-18), normal ranges <45 mcg/24h. Median adrenal adenoma size was 2.2 cm (IQR 1.6-3.0), and median unenhanced HU was 10 (IQR -5 to 22).Median SalF was 52 ng/dL (IQR 23.9-97.5), and median SalE was 332 ng/dL (IQR 222.5-607.0), with a median SalE/SalF ratio of 6.6 (IQR 5.7-9.0). SalF was normal (<50 ng/dL) in 22 (49%) patients with MACS, without differences in the post-dexamethasone cortisol concentrations between those with normal and abnormal SalF (median of 3 mcg/dL vs 3 mcg/dL, P=0.94). SalF correlated with SalE (R2=0.83, P<0.0001). However, only SalE was associated with post-dexamethasone cortisol (R2=0.09, P=0.04). Conclusion: SalE is associated with post-dexamethasone cortisol in patients with MACS and, after an appropriate validation, may provide additional value in support of diagnosis of MACS. Presentation: 6/3/2024