Biochemical markers of skeletal growth in children
This work focused on the application to growth studies of the assay for pyridinium crosslinks in urine. The study showed the existence of a nyctohermeral rhythm of crosslink excretion in children, with a peak during the night or early in the morning, and pointed out between-day fluctuations of excretion (17% for Pyd and 19% for Dpd). The study also showed that urinary crosslinks were significantly related to anthropometric estimates of skeletal mass and that such estimates should be used to account for size differences between individuals. Cross-sectional observations on 272 children (3-18 years) showed a parallelism between the height velocity curve and the age profile of crosslink excretion. In 3-5 year old children, the study pointed out a positive relationship with monthly height velocity (R = 0.20); 5-month integrated values of excretion were also correlated to 5-month height velocity (R = 0.78 for Pyd; R = 0.73 for Dpd). Urinary crosslinks were normal in 53 children (124±34 months) affected by miscellaneous conditions leading to growth defects, in 14 children (117±47 months) affected by coeliac disease, nor in 20 children affected by GH deficiency or short stature (aged 117±20 months); they were in the high range in 7 girls with Turner's syndrome, in 58 malnourished boys (14±14 months), urinary crosslinks were proportional to the degree of wasting and were positively correlated to the rate of height gain during hospitalisation. In children treated with Growth Hormone, except those affected by Turner's syndrome, crosslinks could predict 6-month growth after the first month of therapy.