Calcium retention estimated from indicators of skeletal status in adolescent girls and young women.
To determine clinically useful predictors of calcium retention during postpubertal growth, calcium balance, bio-chemical markers of bone turnover, and anthropometric variables were determined in 14 girls aged 11-14 y and in 11 young women aged 19-30 y. Subjects participated in a 3-wk calcium-balance study with a calcium intake of 1332 mg/d. Biochemical markers of bone turnover (serum osteocalcin, total alkaline phosphatase, bone alkaline phosphatase, tartrate-resistant acid phosphatase, and urinary cross-linked N-teleopeptides of type I collagen and hydroxyproline as the creatinine ratios) were measured in fasting samples. Total-body bone mineral density and total-body calcium content were significantly higher in adults than in adolescents (1.17 compared with 1.05 g/cm2 and 1019 compared with 791 g, respectively). At the observed retention of 326 mg/d, adolescents would require 2 y to reach the total bone calcium of the young adults. All biomarkers of bone turnover were strikingly higher in adolescents than in adults and were strongly correlated with calcium retention. A multiple-regression model using a biochemical marker of bone turnover (serum osteocalcin) and postmenarcheal age (a measure of sexual maturation) described 75% of the variability in calcium retention.
Weaver
C M
CM
Department of Foods and Nutrition, Purdue University, West Lafayette, IN 47907-1264, USA.
Peacock
M
M
Martin
B R
BR
Plawecki
K L
KL
McCabe
G P
GP
D000293:Adolescent; D000328:Adult; D000469:Alkaline Phosphatase / Q000097:blood; D015992:Body Mass Index; D015519:Bone Density; D001842:Bone and Bones / Q000378:metabolism; D002118:Calcium / Q000008:administration & dosage / Q000378:metabolism*; D002648:Child; D003094:Collagen / Q000652:urine; D003404:Creatinine / Q000652:urine; D003432:Cross-Linking Reagents; D005215:Fasting; D005260:Female; D006801:Humans; D006909:Hydroxyproline / Q000652:urine; D015675:Osteocalcin / Q000097:blood; D010446:Peptide Fragments / Q000652:urine; D011627:Puberty
D003432:Cross-Linking Reagents; D010446:Peptide Fragments; D015675:Osteocalcin; D003094:Collagen; D003404:Creatinine; D000469:Alkaline Phosphatase; D006909:Hydroxyproline; D002118:Calcium