Which hormones are involved in the regulation of calcium levels in the body?

The regulation of calcium levels in the body is a complex process involving multiple hormones that work together to maintain homeostasis. The key hormones involved include parathyroid hormone, calcitonin, and vitamin D, each playing a unique role in calcium metabolism.

Parathyroid hormone (PTH) is secreted by the parathyroid glands and is the primary regulator of calcium levels in the blood. It increases blood calcium levels by stimulating the release of calcium from bones, enhancing the reabsorption of calcium by the kidneys, and promoting the activation of vitamin D, which in turn increases intestinal absorption of calcium.

Calcitonin, produced by the thyroid gland, helps to lower blood calcium levels. It acts as a counterbalance to PTH by inhibiting bone resorption (the process of breaking down bone to release calcium into the bloodstream) and increasing calcium excretion in the kidneys.

Vitamin D, particularly its active form calcitriol, is essential for calcium absorption in the intestines and works synergistically with PTH to ensure adequate calcium levels. When calcium levels are low, vitamin D is activated to promote the absorption of calcium from dietary sources.

Therefore, all three components—parathyroid hormone, calcitonin, and vitamin D—play crucial