Reduced bone mineral density and increased bone metabolism rate in young adult patients with 21-hydroxylase deficiency.

ABSTRACT

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.