Normal bone mineral density following cure of Cushing's syndrome

Both endogenous and exogenous glucocorticoid excess are well established as causes of osteoporosis. However, there are few data describing bone mineral density in these subjects following the restoration of normal steroid levels. The present study addresses this issue.

A cross-sectional assessment of bone mineral density in patients cured of Cushing's syndrome, and comparison of each with four normal subjects matched by age, sex, weight, menopausal status and race, was used.

Seventeen adults cured of Cushing's syndrome 8.6 +/- 1.6 years (mean +/- SEM) took part.

The bone mineral density of the lumbar spine and proximal femur was measured by dual energy X-ray absorptiometry.

Bone mineral densities, relative to control, were 100 +/- 16, 98 +/- 14, 97 +/- 19 and 98 +/- 16% (mean +/- SD), in the lumbar spine, femoral neck, Ward's triangle and trochanteric regions, respectively. There was a positive relationship between bone density and time since cure (r = 0.24-0.59, in the four regions). In contrast, bone density was significantly reduced in five subjects with active Cushing's disease when similarly matched (BMD = 87 +/- 4, 83 +/- 4, 75 +/- 6 and 82 +/- 6%, in the respective regions; 0.01 less than P less than 0.05).

Bone density is reduced in subjects with Cushing's syndrome but not in those having undergone cure some years previously. This implies that steroid-induced osteoporosis is substantially reversible, though long-term prospective studies will be necessary to establish this definitively.