URINARY-EXCRETION OF PYRIDINIUM CROSS-LINKS AND N-TERMINAL CROSS-LINKED PEPTIDE IN PRETERM AND TERM INFANTS

Urinary excretion of pyridinium crosslinks of collagen, pyridinoline, deoxypyridinoline, and N-terminal crosslinked peptide are now widely u sed as biochemical markers of bone resorption. In the present cross-se ctional study we measured the urinary excretion of total pyridinoline and total deoxypyridinoline by HPLC and N-terminal crosslinked peptide by ELISA in 43 preterm and term newborns in the first 2 months of lif e. The infants had no history of endocrine or metabolic diseases, bone , chronic heart, or pulmonary diseases. The results were compared by p arametric covariance analysis, the HPLC and ELISA results by the Bland -Altman plot. Preterm infants had a statistically higher level of pyri dinium crosslinks and N-terminal crosslinked peptide in urine (P < 0.0 5) than term infants. The very low birthweight infants (gestational ag e 26-32 weeks) had the highest levels of pyridinoline, deoxypyridinoli ne and N-terminal crosslinked peptide. Levels of both pyridinium cross links and N-terminal crosslinked peptide were independent of sex (P > 0.05). The Bland-Altman plot showed a good agreement between the level s of pyridinium crosslinks and N-terminal crosslinked peptide. Measure ment of pyridinium crosslinks and N-terminal crosslinked peptide excre tion in small infants gives information about skeletal growth and indi vidual bone turnover, which is dependent on gestational age and birthw eight. HPLC and ELISA are reliable methods for the measurement of pyri dinium crosslinks and N-terminal crosslinked peptide, respectively.