Steroid Profiling and Circadian Cortisol Secretion in Patients With Mild Autonomous Cortisol Secretion: A Cross-sectional Study

Context: Mild autonomous cortisol secretion (MACS) is diagnosed based on postdexamethasone cortisol >1.8 mu g/dL. Scarce evidence exists on steroid circadian secretion and steroid metabolome in MACS. Objective To characterize 24-hour (h) urine steroid metabolome in patients with MACS and determine circadian differences in urine steroid profiling and cortisol concentrations in patients with MACS vs referent subjects. Methods: Cross-sectional study, 2018-2023, at a referral center. Patients with MACS and age-, sex-, body mass index-, and menopausal status-matched referent subjects were included. Urine was collected over a 24 hour period as separate daytime and nighttime collections. High-resolution mass spectrometry assay was used to measure 25 steroids. A subgroup of patients and referent subjects was admitted for serum measurements of free and total cortisol every 2 hours. Outcomes were steroids, steroid sums, and ratios. Results: Patients with MACS (n = 72) had lower mu g/24 hour median androgens (2084 vs 3283, P < .001), higher glucocorticoids (15 754 vs 12936, P < .001), and higher glucocorticoid/androgen ratio (8.7 vs 3.9, P < .001) than referent subjects. Patients also had lower steroid day/night ratios than referent subjects, reflecting a higher relative nocturnal steroid production in MACS. In a subgroup of 12 patients with MACS and 10 referent subjects, the 24-hour areas under the curve for total and free serum cortisol were similar. However, evening mean total (5.3 vs 4.0 <mu>g/dL, P = .056) and free (0.2 vs 0.1 mu g/dL, P = .035) cortisol was higher in patients vs referent subjects. Conclusion: Patients with MACS demonstrate an abnormal urine steroid metabolome, with a high glucocorticoid to androgen ratio, and a higher nocturnal steroid production.