INCREASED URINARY-EXCRETION OF COLLAGEN CROSS-LINKS IN GIRLS WITH ULLRICH-TURNER SYNDROME

Skeletal abnormalities and ''osteoporosis'' are frequent features of U llrich-Turner syndrome (UTS), but their cause remains largely unknown. In this study, we compared the urinary excretion of hydroxyproline (O HP), pyridinoline (PYD) and deoxypyridinoline (DPD) in 28 girls (bone age 3.5-11.0 years, mean 7.4 years) with UTS and 30 healthy prepuberta l children (chronological age 3.9-10.9 years, mean 7.6 years). Express ed relative to the square of the height, the excretion of both collage n crosslinks was significantly higher in UTS than in controls (23.4% f or PYD, 33.6% for DPD, p < 0.05). In contrast, no significant differen ce was found for OHP. The molar PYD/DPD ratio was significantly lower in UTS children than in controls (mean (+/- SD) 3.4 (+/- 0.41) versus 3.8 (+/-0.55); p = 0.004). While the higher excretion of collagen cros slinks reflects enhanced bone resorptive activity in UTS, the lower PY D/DPD ratio might be due to structural alterations in collagen.