URINARY GALACTOSYL-HYDROXYLYSINE - A MARKER OF HEIGHT VELOCITY

Abstract

In practical pediatric endocrinology assessment of current height velocity (HV) plays an important role for diagnosis and treatment of growth disorders. However, to date, there is no quick and simple method to determine HV. Urinary excretion of Galactosyl-hydroxylysine (GHLy), a marker of osteoclast activity, has been shown to closely reflect the activity of bone metabolism in adults. In this study we tested the hypothesis that GHLy can also be used to evaluate skeletal growth in children. GHLy was measured in 24h-urines of 74 healthy children, 21 girls with Turner's syndrome (TU) and 15 children with growth hormone deficiency (GHD). HV was calculated from two measurements of body height 6 to 12 months apart. When related to body weight, the 24h excretion of GHLy showed a highly significant correlation to HV in normal children (r=0.75, p 0.05). Data for weight-adjusted daily excretion of GHLy were transformed to standard deviation scores (SDS) to allow for comparison in different age groups. The mean SDS of both GHD and TU were significantly below zero (−1.31 and −1.83 respectively; p<0.05). None of the values in these two disorders was above the mean for healthy children of the same age. Thus, GHLy might be a useful indicator of HV for the evaluation of growth disorders. Further studies arc needed to test if GHLy excretion can be used to predict the changes of HV during growth-promoting therapies.