Determinants of vertebral mineral density in patients receiving long-term glucocorticoid therapy.

This study addresses the impact of clinical and biochemical factors on the bone density of patients receiving glucocorticoid therapy. Vertebral mineral density was measured by quantitative computed tomography in 35 patients aged 17 to 77 years who had received therapeutic glucocorticoid drugs for 0.1 to 22 years. The mean (+/- SEM) vertebral mineral density z score in the subjects was -1.7 +/- 0.2. z score was unrelated to underlying diagnosis, sex, or age but was significantly related to the duration of previous steroid therapy (r = -.38) and to the total cumulative glucocorticoid dose (r = -.50). The rate of change of bone density in 16 of these subjects followed up over a period of 12 months was -8.9% and was significantly greater in subjects taking more than 12.5 mg of prednisone per day. Bone loss was not influenced by sex, age, duration of previous steroid treatment, or diagnosis and was not predictable from biochemical measures of calcium metabolism.