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 µg/dL (33 nmol/L, area under the curve 0.620 ± 0.39; = .002). Compared with controls and NFAI patients with F-1mgDST less than 1.2 µg/dL (group A), NFAI patients with F-1mgDST greater than or equal to 1.2 µg/dL (group B) showed a higher VFx prevalence (10.8%, 12.6%, and 29.5%, respectively; < .001 all comparisons), which was associated with F-1mgDST greater than or equal to 1.2 µg/dL (odds ratio 3.02; 95% CI, 1.63-5.58; < .001) accounting to confounders. Longitudinal arm: the VFx incidence was higher in group B than in group A (19.3% vs 3.6%; = .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 µg/dL, although statistical significance was not reached after adjustment for confounders ( = .061).

CONCLUSION

In NFAI patients, F-1mgDST levels greater than or equal to 1.2 µg/L (33 nmol/L) are associated with prevalent VFx and may identify patients at risk of incident VFx.