Finally, vitamin D promotes calcium absorption in the gut, so it increases serum calcium, promoting bone formation and decreasing bone resorption.

最后，维生素D促进钙在肠内的吸收，因此增加了血清钙的水平，促进骨生长并减弱骨吸收。

When serum calcium level is low, PTH is up regulated.

当血清钙水平较低时，PTH升高。

Factors that accelerate bone mass loss and increase the risk of osteoporosis are low estrogen levels, like after menopause, and low serum calcium.

加剧骨量流失和增加骨质疏松风险的因素有：绝经后较低的雌激素水平，以及较低的血清钙水平。

This feedback loop keeps serum calcium concentrations within the normal range.

该反馈回路将血清钙浓度保持在正常范围内。

Parathyroid hormone is produced by the parathyroid glands in response to low serum calcium, and it increases bone resorption to release calcium into the bloodstream.

顾名思义，甲状旁腺激素在甲状旁腺产生，来应对血清中过低的钙水平，从而增加骨质的吸收来释放更多的钙进入血液。

Because the total serum calcium includes albumin bound and free ionized calcium, of which only the latter is physiologically active.

因为血清总钙包括白蛋白结合钙和游离钙，其中只有游离钙具有生理活性。

Hypocalcemia refers to abnormally low levels of calcium in the blood and is generally defined as serum calcium level lower than 2.1 millimoles per liter.

低钙血症指血液中钙含量异常低，通常定义为血清钙含量低于2。1mmol/L。

Bone remodelling as a whole is highly dependent on serum calcium levels, which, in turn, are kept in the normal range by a balance between parathyroid hormone, or PTH, calcitonin and vitamin D.

整个骨重建进程高度依赖于血清中钙的含量，而将血清中钙的含量维持在正常值范围内是由甲状旁腺激素、降血钙素与维生素D间的制约平衡所控制的。

On the other hand, calcitonin is produced by the thyroid gland in response to high serum calcium, so it opposes the action of PTH - therefore promoting bone formation and decreasing bone resorption.

另一方面，当血清中钙含量较高时，甲状腺释放降血钙素，来制约甲状旁腺激素的作用，从而促进骨骼的形成并减缓骨骼的吸收。

For example, decreased albumin levels such as in liver diseases, nephrotic syndrome, or malnutrition produce lower serum calcium values, but the amount of free calcium may still be normal.

例如，白蛋白水平降低（例如在肝脏疾病，肾病综合症或营养不良中）会产生较低的血清钙值，但游离钙的含量可能仍是正常的。