Bristow S M, Gamble G D, Pasch A, O'Neill W C, Stewart A, Horne A M, Reid I R
University of Auckland, Auckland, New Zealand.
Department of Clinical Chemistry, University Hospital Bern, Inselspital, Bern, Switzerland.
Osteoporos Int. 2016 Mar;27(3):1209-1216. doi: 10.1007/s00198-015-3372-y. Epub 2015 Oct 22.
Calcium supplements have been associated with increased cardiovascular risk, but the mechanism is unknown. We investigated the effects of calcium supplements on the propensity of serum to calcify, based on the transition time of primary to secondary calciprotein particles (T50). Changes in serum calcium were related to changes in T50.
Calcium supplements have been associated with increased cardiovascular risk; however, it is unknown whether this is related to an increase in vascular calcification.
We investigated the acute and 3-month effects of calcium supplements on the propensity of serum to calcify, based on the transition time of primary to secondary calciprotein particles (T50), and on three possible regulators of calcification: fetuin-A, pyrophosphate and fibroblast growth factor-23 (FGF23). We randomized 41 postmenopausal women to 1 g/day of calcium as carbonate, or to a placebo containing no calcium. Measurements were performed at baseline and then 4 and 8 h after their first dose, and after 3 months of supplementation. Fetuin-A, pyrophosphate and FGF23 were measured in the first 10 participants allocated to calcium carbonate and placebo who completed the study.
T50 declined in both groups, the changes tending to be greater in the calcium group. Pyrophosphate declined from baseline in the placebo group at 4 h and was different from the calcium group at this time point (p = 0.04). There were no other significant between-groups differences. The changes in serum total calcium from baseline were significantly related to changes in T50 at 4 h (r = -0.32, p = 0.05) and 8 h (r = -0.39, p = 0.01), to fetuin-A at 3 months (r = 0.57, p = 0.01) and to pyrophosphate at 4 h (r = 0.61, p = 0.02).
These correlative findings suggest that serum calcium concentrations modulate the propensity of serum to calcify (T50), and possibly produce counter-regulatory changes in pyrophosphate and fetuin-A. This provides a possible mechanism by which calcium supplements might influence vascular calcification.
钙补充剂与心血管疾病风险增加有关，但其机制尚不清楚。我们基于初级钙蛋白颗粒向次级钙蛋白颗粒的转变时间（T50），研究了钙补充剂对血清钙化倾向的影响。血清钙的变化与T50的变化相关。
钙补充剂与心血管疾病风险增加有关；然而，这是否与血管钙化增加有关尚不清楚。
我们基于初级钙蛋白颗粒向次级钙蛋白颗粒的转变时间（T50），以及三种可能的钙化调节因子：胎球蛋白-A、焦磷酸盐和成纤维细胞生长因子-23（FGF23），研究了钙补充剂对血清钙化倾向的急性和3个月影响。我们将41名绝经后女性随机分为两组，一组每天服用1克碳酸钙，另一组服用不含钙的安慰剂。在基线时、首次服药后4小时和8小时以及补充3个月后进行测量。对分配到碳酸钙组和安慰剂组并完成研究的前10名参与者测量了胎球蛋白-A,焦磷酸盐和FGF23。
两组的T50均下降，钙组的变化趋势更大。安慰剂组的焦磷酸盐在4小时时从基线下降，此时与钙组不同（P = 0.04）。两组之间没有其他显著差异。血清总钙相对于基线的变化与4小时（r = -0.32，P = 0.05）和8小时（r = -0.39，P = 0.01）的T50变化、3个月时的胎球蛋白-A变化（r = 0.57，P = 0.01）以及4小时时的焦磷酸盐变化（r = 0.61，P = 0.02）显著相关。
这些相关性研究结果表明，血清钙浓度可调节血清钙化倾向（T50），并可能在焦磷酸盐和胎球蛋白-A中产生反调节变化。这为钙补充剂可能影响血管钙化提供了一种可能的机制。
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