Increased Risk of Vertebral Fractures in Patients With Mild Autonomous Cortisol Secretion.

Context: The risk of vertebral fractures (VFx) in patients with adrenal incidentalomas (AI) and mild autonomous cortisol secretion (MACS) is debated.

Objective: To evaluate the VFx prevalence and incidence in patients with AI and MACS.

Methods: This cross-sectional and longitudinal study using retrospective data from 4 Italian endocrinology units included 444 patients (cross-sectional arm) and 126 patients (longitudinal arm, 24.9 ± 5.3 months follow-up) to evaluate prevalent and incident VFx, respectively, in patients with MACS (MACS-yes) and without MACS (MACS-no). The main outcome measures were serum cortisol after a 1-mg dexamethasone test (F-1mgDST), bone mineral density (BMD) by dual-energy x-ray absorptiometry at spine (LS) and femur (FN), and VFx presence by x-ray.

Results: Cross-sectional arm: 214 and 230 patients were MACS-yes and MACS-no, respectively, based on F-1mgDST >1.8 µg/dL (50 nmol/L). Patients with MACS had higher VFx prevalence (62.6%) than those without MACS (22.9%, P < .001); MACS was associated with prevalent VFx (odds ratio, 5.203; 95% CI, 3.361-8.055; P < .001; relative risk [RR] 2.07), regardless of age, body mass index, gender distribution, LS-BMD, and presence of type 2 diabetes mellitus (T2D). Longitudinal arm: 66 and 60 patients were MACS-no and MACS-yes, respectively. Patients without MACS showed higher number of incident VFx (36.4%) than patients without MACS (10.0%, P < .001); MACS was associated with the presence of an incident VFx (RR 4.561; 95% CI, 1.600-13.003; P = .005) regardless of age, LS-BMD, gender distribution, presence of prevalent VFx, and T2D. Results were confirmed in women and men when separately evaluated.

Conclusion: Women and men with AI and MACS are at higher risk of VFx.