Differential effects of inhaled budesonide on serum osteocalcin in children and adolescents with asthma

Abstract

In recent years, measurement of serum osteocalcin has been introduced for assessment of bone turnover in patients treated with exogenous glucocorticoids. Studies in children with asthma on inhaled glucocorticoids, however, have shown inconsistent results. The aim of the present study is to assess bone turnover in prepubertal children and in adolescents with asthma treated with inhaled budesonide using three different osteocalcin assays: the Pharmacia Osteocalcin CAP FEIA, the CIS OSTK-PR and CIS IRMA ELSA-OSTEO assays. Two studies were conducted: 1) a randomised double blind two-period crossover study of 22 prepubertal children aged 5-12 years. In one period 800 microg budesonide was given once in the morning, in the other 400 microg was given twice daily; 2) a randomised double blind placebo controlled two period crossover study of inhaled budesonide 400 microg twice daily in fourteen 13-16 year old adolescents with pubertal stages II-V. In both studies, treatment periods were of four weeks duration, and blood samples were collected at the last day of each period. In the prepubertal children none of the osteocalcin assays detected any statistically significant differences between any of the periods. In the adolescent group reduced levels of osteocalcin were seen during budesonide treatment. The suppression reached statistical significance with the CAP FEIA (P = 0.03) and the OSTK-PR (P = 0.01) assays, but not with the ELSA-OSTEO assay (P = 0.06). Correlation analyses showed statistically significant correlation coefficients varying between 0.58 and 0.91 (P = 0.03 and P < 0.0001, respectively). The effect of inhaled glucocorticoids on serum osteocalcin may depend on the assay applied, and inhaled glucocorticoids have differential effects in children and adolescents.