Reduced Bone Mineral Density and Increased Bone Metabolism Rate in Young Adult Patients with 21-Hydroxylase Deficiency

Context: Patients with congenital adrenal hyperplasia (CAH) receive glucocorticoids as replacement therapy. Glucocorticoid therapy is the most frequent cause of drug-induced osteoporosis. Objective: The objective of the study was to evaluate bone mineral density (BMD) and bone metabolism in CAH patients. Design: This was a cross-sectional observational study. Setting: The study was conducted at a referral center for pediatric endocrinology. Patients and Other Participants: Thirty young patients with the classical form of CAH (aged 16.4–29.7 yr) treated with glucocorticoid from diagnosis (duration of treatment 16.4–29.5 yr) and 138 healthy controls (aged 16.0–30.0 yr) were enrolled. Main Outcome Measures: BMD was measured in the lumbar spine and whole body by dual-energy x-ray absorptiometry. Bone formation and resorption rates were estimated by serum measurements of bone-specific alkaline phosphatase and C-terminal telopeptide of type I collagen, respectively. Results: CAH patients were shorter than controls (women −6.8 and men −13.3 cm). Therefore, several methods were used to account for the effect of this difference on bone measurements. Whole-body BMD measurements were significantly lower, compared with controls (P < 0.03), after controlling for height (on average −2.5% in females and −9.3% in male patients). No differences were found in lumbar spine measurements. Bone-specific alkaline phosphatase and C-terminal telopeptide of type I collagen serum concentrations were higher in CAH patients than control subjects (P < 0.04). BMD measurements and bone metabolism markers did not correlate with the actual glucocorticoid dose or mean dose over the previous 7 yr. Conclusions: Young adult patients with the classical form of CAH have decreased bone density values, compared with healthy controls. This may put them at risk of developing osteoporosis early in life.