TABLE 2.
Biochemical bone markers at baseline and at the end of each 3-wk metabolic period under the low and high calcium intakes in Mexican-American boys and girls1
| Baseline |
Low calcium intake (631–1275 mg/d) |
High calcium intake (1118–2157 mg/d) |
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| Biomarkers | Boys (n = 20) | Girls (n = 20) | Boys (n = 20) | Girls (n = 20) | Boys (n = 20) | Girls (n = 20) |
| Serum total alkaline phosphatase, U/L | 241 ± 81 | 142 ± 53* | 219 ± 69 | 133 ± 38* | 224 ± 72 | 140 ± 60* |
| Serum calcium, ng/dL | 9.91 ± 0.27 | 9.92 ± 0.28* | 9.57 ± 0.23 | 9.83 ± 0.27* | 9.60 ± 0.24 | 9.85 ± 0.33* |
| Serum creatinine, ng/dL | 0.92 ± 0.09 | 0.78 ± 0.08* | 0.90 ± 0.09 | 0.77 ± 0.06* | 0.90 ± 0.10 | 0.78 ± 0.07* |
| Serum PTH, pg/mL | 25.1 ± 7.5 | 26.7 ± 9.2 | 28.5 ± 10.7 | 31.6 ± 8.6 | 25.1 ± 10.2 | 27.8 ± 7.4 |
| Serum IGF-1, μg/L | 298 ± 75 | 302 ± 45 | 269 ± 72 | 293 ± 36 | 259 ± 67 | 285 ± 41 |
| Serum IGFBP3, μg/mL | 4.14 ± 1.44 | 3.27 ± 0.61 | 3.88 ± 1.19 | 3.27 ± 0.63 | 3.95 ± 1.27 | 3.12 ± 0.47* |
| Serum 25(OH)D, μg/L | 24.7 ± 3.8 | 22.1 ± 5.3 | 26.6 ± 2.8 | 23.4 ± 6.6 | 26.6 ± 5.3 | 26.2 ± 5.9 |
| Urinary NTx/Cr, nmol BCE/mmol creatinine | 694 ± 391 | 354 ± 165* | 647 ± 347 | 392 ± 194* | 637 ± 330 | 378 ± 198* |
1
Values are means ± SDs. *Different from boys, P < 0.05. BCE, bone collagen equivalent; IGF-1, insulin-like growth factor 1; IGFBP3, insulin-like growth factor binding protein-3; NTx/Cr, N-telopeptide of type I collagen/creatinine ratio; PTH, parathyroid hormone; 25(OH)D, 25-hydroxyvitamin D.