FREE DEOXYPYRIDINOLINE IN URINE AND SERUM - RESULTS IN CHILDREN AND ADOLESCENTS

The urinary excretion of the collagen crosslinking compound deoxypyrid inoline (DPD) is considered a specific index of bone resorption. Here we report on the levels of free (i.e. non peptide-bound) DPD in the ur ine and serum of subjects from 5 to 19 years of age, as determined by a new radioimmunoassay. Reference values for free DPD were established using 24-h urine collections from 118 healthy children and serum samp les from 133 children with acute febrile illnesses. Serum and urine le vels of free DPD were compared in samples from 23 short, normal childr en, Additionally, total (the sum of peptide-bound and free) DPD was me asured by high-performance liquid chromatography in the 24-h urine col lections. Urinary-free DPD was significantly correlated with total DPD (r = 0.90; P < 0.001) and declined steadily with age. Serum levels of free DPD ranged from 0.9 to 5.7 nmol/l and varied with age in boys on ly. No significant association was found between serum and urine level s of free DPD (r = 0.08; P = 0.37). In conclusion, urinary-free DPD di d not reflect enhanced bone turnover during the time of puberty. Free DPD serum levels are very low, which may be due to rapid clearance via the kidneys.