Characterisation of the urinary steroid profile of patients with nonfunctioning adrenal incidentalomas: A matched controlled cross-sectional study.

Aim: To identify alterations in steroid metabolism in patients with nonfunctioning adrenal incidentalomas (NFAIs) through the analysis of their urinary steroid profile (USP).

Methods: Cross-sectional study with one study group (NFAIs, cortisol post dexamethasone suppression test [DST] ≤ 1.8 µg/dl [49.7 nmol/L]) and 2 control groups: patients with autonomous cortisol secretion (ACS group, cortisol post-DST > 1.8 µg/dl (49.7 nmol/L) and patients without adrenal tumours (healthy-adrenal group). Twenty-four-hour urine collections for USP measurement (total and free fraction of 51 24 h-urine specimens) were obtained from 73 participants (24 with NFAIs, 24 without AIs, and 25 with ACS). USP was determined by gas chromatography coupled to mass spectrometry. Patients of the three groups were matched according to sex, age (±5 years-old) and body mass index (±5 kg/m ).

Results: Compared to healthy-adrenal controls, patients with NFAIs had a lower excretion of androgen metabolites (230.5 ± 190.12 vs. 388.7 ± 328.58 µg/24 h, p = .046) and a higher excretion of urinary free cortisol (UFC) (54.3 ± 66.07 vs. 25.4 ± 11.16 µg/24 h, p = .038). UFC was above the reference range in 20.8% of patients in the NFAI, compared to 0% in the healthy-adrenal group (p = .018). Patients with ACS had a higher prevalence of hypertension, dyslipidemia, and diabetes than patients with NFAIs or the control group. A lower excretion of androgen metabolites (218.4 ± 204.24 vs. 231 ± 190 µg/24 h, p = .041) and a nonsignificant higher excretion of glucocorticoid metabolites (2129.6 ± 1195.96 vs. 1550.8 ± 810.03 µg/24 h, p = .180) was found in patients with ACS compared to patients with NFAIs.

Conclusion: NFAIs seem to secrete a subtle, yet clinically relevant, excess of glucocorticoids. Future studies are needed to confirm our findings; and to identify metabolic alterations associated with an increased cardiometabolic risk.