Abstract 123

Both Pyridinoline (Pyd) and Deoxypyridinoline(D-pyd) are released from collagen tissue. They are good markers of bone turnover and hence linear growth in children. There are few data on urinary Pyd and D-pyd in newborn infants, and no data for premature infants. This longitudinal study was designed to evaluate urinary Pyd and D-pyd in VLBW infants in relation to their linear growth velocity over 12 weeks period of postnatal age. Thirty-three infants were included in the study. Birth weight was < 1500 gm (median=1020 gm), and gestation was < 32 weeks (median=28). Weekly measurement of knee-heel length was performed by electronic Knanometer, and free urinary Pyd and D-pyd levels were measured by high performance liquid chromatography technique. Median values for Pyd and D-pyd over the study period were 190.6 nmol/l and 58.3 nmol/l respectively. These values were significantly higher than in full term infants and children. There was significant correlation between D-pyd and gestation (P = 0.002, r = o.573). However, there was no significant correlation between growth velocity(knee-heel length) and D-pyd level. The results suggested that VLBW infants have high levels of urinary Pyd and D-pyd, however changes in growth velocity were not necessarily associated with higher values of urinary Pyd and D-pyd. In conclusion, although this study has confirmed that VLBW infants excrete large amount of both Pyd and D-pyd, their levels were not related to their linear growth velocity. Higher levels seen at higher gestational age probably reflect the exponential increase in bone mineralization. It is unlikely that Pyd and D-pyd would be good markers for metabolic bone disease of prematurity.