Bone mineral density in steroid-dependent asthma assessed by peripheral quantitative computed tomography.

Chronic use of systemic glucocorticoids results in progressive bone loss and pathologic fractures. This study identified the predictive variables for bone loss and used peripheral quantitative computed tomography (pQCT) to measure changes in cortical and trabecular bone in patients receiving systemic glucocorticoid therapy of prednisone 15.4 g. Eighty-four asthmatic patients were included in the study. Vertebral fractures were diagnosed via plain spinal radiograms. pQCT was used to measure cortical and trabecular bone mineral density. Multiple regression analysis identified variables with predictive value. The cumulative dose of glucocorticoid correlated with the bone mineral density (p<0.05) and the trabecular bone density (p<0.01). Among patients > or = 65 yrs of age, the cumulative dose of glucocorticoid correlated with the occurrence of vertebral fractures (p<0.05), total bone mineral density (p<0.01) and cortical bone mineral density (p<0.01). Bone mineral density in the distal radius measured by pQCT and the vertebral bodies by axis QCT were correlated, regardless of whether systemic glucocorticoids were administered. Glucocorticoid administration not only decreases trabecular but also cortical bone mineral density. Since cortical bone provides strength and stiffness, it appears that the loss of cortical bone is responsible for the increased incidence of fracture seen in patients receiving systemic glucocorticoid therapy.