Collagen metabolism and growth in prepubertal children with asthma treated with inhaled steroids

Objective: To investigate growth and markers of collagen and bone metabolism in prepubertal children with asthma. Study design: We measured growth velocity over 12 months and markers of collagen types I and III synthesis (PINP, PICP, PIIINP), collagen type I degradation (ICTP), and bone metabolism (bone-specific alkaline phosphatase and osteocalcin) on one occasion in 56 prepubertal children with stable asthma, 39 of whom were treated with inhaled budesonide or beclomethasone. Collagen data were compared with normal control values. Results: Children treated with inhaled steroids had reduced collagen synthesis (PINP, PIIINP) compared with control subjects (p = 0.038, p = 0.045), although PICP was increased (p = 0.05). Carboxyterminal telopeptide of type I collagen was reduced in patients treated with inhaled steroids (p < 0.0005) compared with nonsteroid-treated patients. Serum osteocalcin but not bone-specific alkaline phosphatase was significantly reduced in children treated with inhaled steroids (p < 0.02). Significant correlation was observed between PIIINP and ICTP and growth velocity. Conclusion: Collagen turnover is reduced in children with asthma receiving long-term inhaled steroid treatment. Markers of collagen synthesis provide a more accurate reflection of growth disturbance than osteocalcin and bone-specific alkaline phosphatase.