title: Elevated collagen turnover in Nigerian children with calcium-deficiency rickets.
abstract: Calcium deficiency is a major etiological determinant of rickets in Nigerian children and is accompanied by undermineralization of the developing bone matrix which is composed largely of type I collagen. We have assessed types I and III collagen metabolism by measuring the circulating concentrations of teh N- and C-terminal pro-peptides (intact PINP and PICP) and the C-terminal telopeptide (ICTP) of type I collagen, and the N-terminal pro-peptide (PIIINP) of type III collagen in 94 healthy Nigerian children and in 44 children aged 1-5 years with active calcium-deficiency rickets. In active rickets the mean levels of the four collagen metabolites were approximately twofold higher than in the healthy children, despite a wide variation of individual values. Mean intact PINP was 812 +/- 279 versus 403 +/- 189 microg/liter; PICP was 573 +/- 265 versus 348 +/- 299 microg/liter; PIIINP was 16.8 +/- 8.6 versus 10.8 +/- 3.6 microg/liter, and ICTP was 28.4 +/- 17.2 versus 11.9 +/- 4.1 microg/liter (all P < 0.001), in rachitic and healthy children, respectively. Healthy children younger than 3 years had higher levels of all the collagen metabolites than those between 3 and 5 years (all P < 0.05). Alkaline phosphatase was greater in rickets than in the healthy group (P < 0.001) whereas mean osteocalcin levels were slightly lower (P = 0.009). 1,25(OH)2D correlated with all the collagen propeptides, but not with ICTP in the healthy children. No such correlations were found in rickets, where there was a poor inverse correlation between 1,25(OH)2D and ICTP. These data suggest that collagen turnover is elevated in cases of calcium-deficiency rickets, where vitamin D status is adequate, possibly indicating increased turnover of undermineralized osteoid.
authors.affiliation: Charles Salt Research Centre, Robert Jones & Agnus Hunt Orthopaedic and District Hospital NHS Trust, Oswestry, Shropshire SY10 7AG, United Kingdom.
authors.forename: C A
authors.initials: CA
authors.lastname: Sharp
authors.forename: L M
authors.initials: LM
authors.lastname: Oginni
authors.forename: M
authors.initials: M
authors.lastname: Worsfold
authors.forename: O A
authors.initials: OA
authors.lastname: Oyelami
authors.forename: L
authors.initials: L
authors.lastname: Risteli
authors.forename: J
authors.initials: J
authors.lastname: Risteli
authors.forename: M W
authors.initials: MW
authors.lastname: Davie
mesh_terms: D001846:Bone Development; D055395:Bone Morphogenetic Protein 1; D019485:Bone Morphogenetic Proteins; D002118:Calcium / Q000172:deficiency*; D002675:Child, Preschool; D003094:Collagen / Q000378:metabolism; D024042:Collagen Type I; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008666:Metalloendopeptidases / Q000378:metabolism; D009549:Nigeria; D010281:Parathyroid Hormone / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D011347:Procollagen / Q000378:metabolism*; D011348:Procollagen N-Endopeptidase / Q000378:metabolism; D012279:Rickets / Q000378:metabolism*; D014807:Vitamin D / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D019485:Bone Morphogenetic Proteins; D024042:Collagen Type I; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide; C041876:procollagen Type III-N-terminal peptide; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; D003094:Collagen; D008666:Metalloendopeptidases; D011348:Procollagen N-Endopeptidase; C525705:BMP1 protein, human; D055395:Bone Morphogenetic Protein 1; D002118:Calcium