Short-term growth and collagen turnover in asthmatic adolescents treated with the inhaled glucocorticoid budesonide

Short-term lower leg growth, the insulin-like growth factor axis, and collagen turnover were assessed in 16 adolescents with asthma during treatment with inhaled budesonide, 800 micrograms/d, from a pressurized metered dose inhaler with a volume spacer. The design was a randomized double blind, placebo-controlled two-period crossover trial with treatment periods of 4 weeks and a 1-week wash-out. Lower leg growth was assessed by knemometry. Serum levels of insulin-like growth factor-I, insulin-like growth factor-binding protein-3, and the following markers of collagen turnover were evaluated: Serum markers of type I collagen formation and degradation; the carboxy-terminal propeptide of type I procollagen and the carboxy terminal pyridinoline cross-linked telopeptide of type I procollagen (ICTP), the serum marker of type III collagen formation; the amino-terminal propeptide of type III procollagen (PIIINP) and the urinary concentrations of the type I collagen degradation products pyridinoline (PYD) and deoxypyridinoline (DPD) cross-links. Mean lower leg growth velocity was suppressed from 0.51 mm/week during placebo to 0.18 mm/week during budesonide treatment (p < 0.001). No statistically significant effects on insulin-like growth factor-1, insulin-like growth faster-binding protein-3, or carboxy-terminal propeptide of type I procollagen were observed. ICTP and PIIINP were reduced with 2.3 and 2.5 micrograms/liter (p < 0.001 and p < 0.001, respectively) during budesonide treatment, urinary concentrations of PYD and DPD with 32.9 nmol/mmol creatinine (p < 0.005) and 6.8 nmol/mmol creatinine (p < 0.005), respectively. Significant correlations between lower leg growth velocity and ICTP, PIIINP, PYD, and DPD during placebo (p < 0.01, p < 0.05, p < 0.01, and p < 0.01) and budesonide (p < 0.05, p < 0.05, p < 0.05, and p < 0.05) periods were found. Short term lower leg growth suppression in adolescents treated with inhaled budesonide, 800 micrograms/d, reflects suppression of type I and III collagen turnover.