title: Markers of type I and III collagen turnover as indicators of growth velocity in very low birth weight infants.
abstract: Monitoring postnatal growth in very low birth weight (VLBW) infants is complicated by the difficulty of obtaining reliable measurements. A need thus exists for safe and reliable indicators of such infants' short-term growth velocity. We set out to study whether markers of type I collagen synthesis [amino-terminal propeptide of type I procollagen (PINP)] or degradation [via the matrix metalloproteinase pathway, carboxyl-terminal telopeptide of type I collagen (ICTP)] or of type III collagen synthesis [amino-terminal propeptide of type III procollagen (PIIINP)] could serve as such indicators. PINP, ICTP, and PIIINP were measured for 48 VLBW infants (mean birth weight, 923 g; range, 540-1485 g; mean gestational age, 27.6 wk; range, 23.7-32.7 wk) at the age of 1, 2, 4, and 8 wk. At each time point, these were compared with concurrent growth velocity rigorously assessed by frequent lower leg (knemometry) and weight measurements. PINP showed a significant positive correlation with lower leg growth velocity at 1, 2, and 4 wk and with weight growth velocity at 2, 4, and 8 wk. PIIINP showed a significant positive correlation with lower leg growth at 1, 2, and 8 wk and with weight growth at 2 and 8 wk. The ICTP/PINP ratio, reflecting type I collagen degradation in relation to its synthesis, showed close negative correlations with lower leg growth at 1 wk (r = -0.46; P = 0.003), 2 wk (r = -0.51; P = 0.002), and 4 wk (r = -0.56; P = 0.001) and with weight growth at 2 wk (r = -0.39; P = 0.018), 4 wk (r = -0.59; P = 0.0003), and 8 wk (r = -0.53; P = 0.005). A high ICTP/PINP ratio was an accurate predictor of impaired growth; a high ICTP/PINP ratio was a more rapid and at least as sensitive and specific indicator of slow growth as weight gain. We conclude that PINP, PIIINP, and the ICTP/PINP ratio all reflect postnatal growth velocity in VLBW infants. The most robust of these indicators is the ICTP/PINP ratio, which may thus serve as a clinical tool in assessing short-term growth of these infants.
authors.affiliation: The Hospital for Children and Adolescents, Helsinki University Central Hospital, 00029 HUS Helsinki, Finland. eero.kajantie@hus.fi
authors.forename: E
authors.initials: E
authors.lastname: Kajantie
authors.forename: L
authors.initials: L
authors.lastname: Dunkel
authors.forename: J
authors.initials: J
authors.lastname: Risteli
authors.forename: M
authors.initials: M
authors.lastname: Pohjavuori
authors.forename: S
authors.initials: S
authors.lastname: Andersson
mesh_terms: D015415:Biomarkers; D003094:Collagen / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology; D005500:Follow-Up Studies; D005865:Gestational Age; D006128:Growth / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight / Q000254:growth & development*; D011347:Procollagen / Q000378:metabolism; D011506:Proteins / Q000378:metabolism
chemical_list: D015415:Biomarkers; D011347:Procollagen; D011506:Proteins; D003094:Collagen