URINARY-EXCRETION OF PYRIDINIUM CROSS-LINKS OF COLLAGEN IN INFANCY

This cross-sectional study evaluated urinary excretion of pyridinium c ross-links of collagen, specific markers of ongoing hone resorption, i n infants aged 1 week to 7 months and examined the relationship betwee n urinary cross links and individual renal function. Spot urines from a total of 100 infants were analyzed. The collagen cross-links, pyridi noline (Pyd) and deoxypyridinoline (D-Pyd), were assayed by fluorescen ce detection after high-performance liquid chromatography (HPLC). beta (2)-Microglobulin (beta(2)M), an index of renal tubular function, was determined by radioimmunoassay. In healthy term infants, urinary colla gen cross-links were several times higher than the reported data for o lder children, with peak values seen at 1 month of age. Excretion of P yd and D-Pyd was also markedly elevated in 1-month-old preterm infants , despite poor somatic growth. Such high excretion of collagen cross-l inks probably reflects the state of accelerated bone turnover in infan cy. The postnatal change in the doss-links was different from that in urinary beta(2)M, and the values obtained did not correlate with beta( 2)M in either term or preterm infants. These results indicate that cro ss-link excretion is not influenced directly by individual renal funct ion. (C) 1996 by W.B. Saunders Company