O'Brien Kimberly O, Donangelo Carmen M, Zapata Carmiña L Vargas, Abrams Steven A, Spencer E Martin, King Janet C
Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA.
Am J Clin Nutr. 2006 Feb;83(2):317-23. doi: 10.1093/ajcn/83.2.317.
Few data exist on longitudinal changes in bone calcium turnover rates across pregnancy and lactation.
Our aim was to characterize calcium kinetic variables and predictors of these changes across pregnancy and early lactation in women with low calcium intakes.
Stable calcium isotopes were administered to 10 Brazilian women during early pregnancy (EP; weeks 10-12 of gestation), late pregnancy (LP; weeks 34-36 of gestation), and early lactation (EL; 7-8 wk postpartum). Multicompartmental modeling was used to assess the rates of bone calcium turnover in relation to calcium intakes and circulating concentrations of parathyroid hormone (PTH), insulin-like growth factor 1, and 1,25-dihydroxyvitamin D.
Rates of bone calcium deposition increased significantly from EP to LP (P = 0.001) and were significantly associated with serum PTH during LP (P < or = 0.01). Rates of bone calcium resorption were also higher during LP and EL than during EP (P < or = 0.01) and were associated with both PTH (P < or = 0.01) and IGF-1 (P < or = 0.05) during LP but not during EL. Net balance in bone calcium turnover was positively associated with dietary calcium during EP (P < or = 0.01), LP (P < or = 0.01), and EL (P < or = 0.01). The mean (+/-SD) calcium intake was 463 +/- 182 mg/d and, in combination with insulin-like growth factor 1, explained 68-94% of the variability in net bone calcium balance during pregnancy and lactation.
Net deficits in bone calcium balance occurred during pregnancy and lactation. Increased dietary calcium intake was associated with improved calcium balance; therefore, greater calcium intakes may minimize bone loss across pregnancy and lactation in women with habitual intakes of <500 mg calcium/d.
关于孕期和哺乳期骨钙周转率的纵向变化的数据很少。
我们的目的是描述钙摄入量低的女性在孕期和哺乳期早期钙动力学变量及其变化的预测因素。
对10名巴西女性在孕早期（EP；妊娠10 - 12周）、孕晚期（LP；妊娠34 - 36周）和哺乳期早期（EL；产后7 - 8周）给予稳定钙同位素。采用多室模型评估骨钙周转率与钙摄入量以及甲状旁腺激素（PTH）、胰岛素样生长因子1和1,25 - 二羟基维生素D循环浓度之间的关系。
从EP到LP，骨钙沉积率显著增加（P = 0.001），并且在LP期间与血清PTH显著相关（P≤0.01）。LP和EL期间的骨钙吸收率也高于EP期间（P≤0.01），在LP期间与PTH（P≤0.01）和IGF - 1（P≤0.05）均相关，但在EL期间与二者均无关。骨钙周转的净平衡在EP（P≤0.01）、LP（P≤0.01）和EL（P≤0.01）期间与膳食钙呈正相关。平均（±标准差）钙摄入量为463±182mg/d，并且与胰岛素样生长因子1共同解释了孕期和哺乳期骨钙净平衡变异性的68 - 94%。
孕期和哺乳期出现骨钙平衡净亏空。膳食钙摄入量增加与钙平衡改善相关；因此，对于习惯性钙摄入量<500mg/d的女性，增加钙摄入量可能会使孕期和哺乳期的骨质流失最小化。
