Context: Patients with congenital adrenal hyperplasia (CAH) receive glucocorticoids as replacement therapy. Glucocorticoid therapy is the most frequent cause of drug-induced osteoporosis.

Objective: To evaluate bone mineral density (BMD) and bone metabolism in CAH patients.

Design: 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 (ages, 16.4 to 29.7 yr) treated with glucocorticoid from diagnosis (duration of treatment, 16.4 to 29.5 yr), and 138 healthy controls (ages, 16.0 to 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 (BALP) and C-terminal telopeptide of type I collagen (CTX), 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. BALP and CTX serum concentrations were higher in CAH patients than in control subjects (P < 0.04). BMD measurements and bone metabolism markers did not correlate with the actual glucocorticoid dose or with the 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.