High-turnover osteopenia in preterm infants: determination of urinary pyridinium cross-links of collagen.
Osteopenia is a frequent condition in preterm infants, but its pathogenesis is uncertain. In the present study, we measured longitudinal changes in the excretion of pyridinium cross-links of collagen (specific markers of bone resorption) and evaluated the relationship between collagen cross-links and other indexes of bone and renal function in preterm infants. In these infants, urinary collagen cross-links were markedly increased on day 7 and day 30 of life and at estimated full-term gestation. The values were several times higher than those of older children and almost comparable to those of healthy full-term infants. Cross-link excretion did not correlate with beta2-microglobulin (B2M) or N-acetyl-beta-D-glucosaminidase (NAG) activity (markers of renal function), indicating that cross-link excretion is not influenced directly by infantile renal function. High serum osteocalcin and low bone mineral density (BMD) in the lumbar spine were also observed at estimated full-term gestation. There was no significant correlation between collagen cross-link excretion and either serum osteocalcin or spine BMD. We conclude that a state of high bone turnover underlies the development of osteopenia in preterm infants.
Tsukahara
H
H
Department of Pediatrics, Fukui Medical School, Japan.
Takeuchi
M
M
Fujisawa
K
K
Miura
M
M
Hata
K
K
Yamamoto
K
K
Mayumi
M
M
D000375:Aging; D000596:Amino Acids / Q000652:urine*; D015519:Bone Density; D001851:Bone Diseases, Metabolic / Q000209:etiology / Q000652:urine*; D016723:Bone Remodeling; D003094:Collagen / Q000652:urine; D024042:Collagen Type I; D003404:Creatinine / Q000652:urine; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000652:urine*; D008297:Male; D010455:Peptides / Q000652:urine
D000596:Amino Acids; D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; C015484:pyridinoline; C036020:deoxypyridinoline; D003094:Collagen; D003404:Creatinine