Urinary immunoreactive deoxypyridinoline in children and adolescents: variations with age, sex and growth velocity.

The collagen cross-linking compound deoxypyridinoline (DPD) has been shown to be a marker of bone resorption and skeletal growth in children. However, the original method for the determination of total (i.e. free and peptide-bound) DPD (tDPD) in urine samples is technically demanding. The recent development of a simple enzyme-linked immunosorbent assay for the quantification of immunogenic DPD (iDPD) in urine samples might be a more convenient technique. Yet, it is unclear at present whether iDPD is equal to tDPD as an index of bone resorption and skeletal growth. Therefore, using 24-h urines from 144 healthy children and adolescents aged 4-19 years, we established reference ranges for the daily urinary excretion of iDPD. A close correlation was found between the daily urinary excretion of iDPD and tDPD related to body weight (r = 0.87, p < 0.001). In 72 subjects aged 4-18 years, the daily excretion of iDPD normalized to body weight was highly significantly correlated with growth velocity (r = 0.70, p < 0.001). We conclude that the enzyme-linked immunosorbent assay for urinary iDPD appears to provide a good index of bone resorption and growth in healthy children.