Skeletal differences in bone mineral area and content before and after cure of endogenous Cushing's syndrome

Abstract

We examined bone densitometric data in a four-year follow-up period before and after the cure of CS. Plasma cortisol concentrations were similar, but the duration of estimated glucocorticoid excess was longer in patients with prevalent bone fractures compared to those without fractures. After therapy of CS, bone area, BMC and BMD increased significantly at the LS and femur during follow-up, but they decreased at the forearm, suggesting redistribution of bone minerals from the peripheral to the axial skeleton.

Introduction: Only a few studies report the changes in bone mineral density (BMD) after the cure of Cushing's syndrome (CS).

Methods: Forty-one patients with Cushing's disease, 21 patients with adrenal CS and 6 patients with ectopic CS were prospectively enrolled. BMD, bone mineral content (BMC) and bone area were measured by DXA.

Results: No significant correlations were found between serum cortisol concentrations and baseline bone densitometric data. After successful therapy of CS, bone area and BMD increased significantly at the lumbar spine (LS) and femur during follow-up, but they decreased at the forearm. The progressive increase in BMC at the LS had a significant negative correlation with the change of the BMC of radius in the first and second follow-up years. The change in the body mass index was an independent predictor for changes in BMC both at the LS and at the forearm at the second year of remission.

Conclusions: The regional differences and the time-dependent changes of BMC suggest that the source of marked increase in axial BMC after the cure of CS is, at least partly, due to the redistribution of bone minerals from the peripheral to the axial skeleton.