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.