Fragility Fractures and Cortisol Secretion in Patients With Nonfunctioning Adrenal Incidentalomas

Context: The risk of vertebral fractures (VFx) in patients with nonfunctioning adrenal incidentalomas (NFAI) is unknown. Objective: This work aimed to assess in NFAI patients the prevalence and incidence of VFx and a hormonal marker to identify patients at risk. Methods: A retrospective, cross-sectional, and longitudinal study of outpatients was conducted. A total of 306 NFAI patients (cross-sectional arm) and 213 controls were evaluated for VFx prevalence; 85 NFAI patients (longitudinal arm, follow-up 30.3 +/- 17.5 months) were evaluated for VFx incidence. Main outcome measures included serum cortisol after 1 mg-dexamethasone test (F-1mgDST), lumbar spinal (LS), and femoral neck (FN) bone mineral density (BMD) and VFx presence, by radiograph of the spine. Results: Cross-sectional arm: prevalent VFx associated with F-1mgDST with a cutoff of 1.2 mu g/dL (33 nmol/L, area under the curve 0.620 +/- 0.39; P = .002). Compared with controls and NFAI patients with F-1mgDST less than 1.2 mu g/dL (group A), NFAI patients with F-1mgDST greater than or equal to 1.2 mu g/dL (group B) showed a higher VFx prevalence (10.8%, 12.6%, and 29.5%, respectively; P < .001 all comparisons), which was associated with F-1mgDST greater than or equal to 1.2 <mu>g/dL (odds ratio 3.02; 95% CI, 1.63-5.58; P < .001) accounting to confounders. Longitudinal arm: the VFx incidence was higher in group B than in group A (19.3% vs 3.6%; P = .05). In group B, all incident VFx occurred in patients without low BMD. The F-1mgDST cutoff for predicting an incident VFx was 1.2 <mu>g/dL, although statistical significance was not reached after adjustment for confounders (P = .061). Conclusion: In NFAI patients, F-1mgDST levels greater than or equal to 1.2 mu g/L (33 nmol/L) are associated with prevalent VFx and may identify patients at risk of incident VFx.