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 post-dexamethasone cortisol>1.8 mcg/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 versus referent subjects.

Design: Cross-sectional study, 2018-2023.

Setting: Referral center.

Participants: Patients with MACS and age-, sex-, BMI-, and menopausal status-matched referent subjects.

Measurements: Urine was collected over 24h period as separate day- and night-time collections. High-resolution mass spectrometry assay was used to measure 25 steroids. A subgroup of patients and referent subjects were admitted for every 2h serum measurements of free and total cortisol.

Outcomes: Steroids, sums, and ratios.

Results: Patients with MACS (n=72) had lower mcg/24h median androgens (2084 vs 3283, P<0.001), higher glucocorticoids (15754 vs 12936, P<0.001), and higher glucocorticoid/androgen ratio (8.7 vs 3.9, P<0.001), compared to referent subjects. Patients also had lower steroid day/night ratios compared to 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 area under the curves for total and free cortisol were similar. However, evening mean total (5.3 vs 4.0 mcg/dL, P=0.056) and free (0.2 vs 0.1 mcg/dL, P=0.035) 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.