Urinary pyridinoline and deoxypyridinoline in healthy children and in children with growth hormone deficiency.

To assess the bone growth status in healthy children, urinary pyridinoline (PYR) and deoxypyridinoline (DPYR) levels, which are specific bone resorption markers, were studied in 192 healthy children, aged 3-14 yr. In healthy children ages 3-5 yr, the urinary PYR level was about 10 times higher than that in healthy adults (238.3 +/- 22.7 pmol/mumol Cr in boys and 261.8 +/- 14.2 pmol/mumol Cr in girls; mean +/- SE, and the level declined gradually with age. In boys, the urinary PYR level began to rise at about 10 yr of age and peaked 2 yr later, declining thereafter. In girls, urinary PYR level declined rapidly after 11 yr. The age-related changes in urinary DPYR levels closely resembled those in urinary PYR levels. We further studied PYR and DPYR levels in 17 GH-deficient children who were beginning treatment with GH. After 2-3 months of GH therapy, 1.3-fold significant increases in urinary PYR and DPYR levels were observed. These results indicate that the bone resorption in children is increased relative to that in adults, that urinary PYR and DPYR levels are increased during puberty when the growth rate is markedly elevated, and that bone resorption in children is accelerated by GH therapy.