Trabecular bone score and bone mineral density as indices of skeletal fragility in endogenous Cushing's syndrome.

OBJECTIVE

Endogenous Cushing's syndrome (CS) is a known cause of secondary osteoporosis. Vertebral fractures (VFs) in endogenous CS may occur despite normal bone mineral density (BMD). Trabecular bone score (TBS) is a relatively new, non-invasive technique to assess bone microarchitecture. The objective of our study was to analyse the BMD and bone microarchitecture using TBS in endogenous CS and compare it with a group of age and sex-matched healthy controls, and also analyse the factors predicting BMD and TBS.

DESIGN

Cross-sectional study of cases and controls.

PATIENTS AND MEASUREMENTS: We included 40 female patients with overt endogenous CS, out of which 32 were adrenocorticotropic hormone (ACTH)-dependent CS and 8 were ACTH-independent. We also included 40 healthy, female controls. Both patients and controls were subjected to an assessment of biochemical parameters and BMD and TBS.

RESULTS

Patients with endogenous CS had significantly lower BMD at the lumbar spine, femoral neck, and total hip and significantly lower TBS than healthy controls (all p < .001), while no significant difference was noted in the distal radius BMD (p = .055). In endogenous CS, a large proportion of patients, n = 13 (32.5%) had normal BMD for age (BMD Z-score ≥ -2.0) with low TBS (L1 -L4 TBS ≤ 1.34). TBS correlated negatively with HbA1c (p = .006), and positively with serum T4 (p = .027).

CONCLUSION

TBS should be considered an important complementary tool in addition to BMD for the routine assessment of skeletal health in CS.