Which hormone regulates calcium levels?

The hormone that regulates calcium levels is parathyroid hormone (PTH), which is produced by the parathyroid glands. When calcium levels in the blood are low, PTH is released into the bloodstream. It functions to increase calcium levels by promoting the release of calcium from bones, enhancing the absorption of calcium in the intestines, and increasing the reabsorption of calcium in the kidneys. This regulation is crucial because calcium plays several important roles in the body, including muscle contraction, nerve function, and blood clotting.

In contrast, insulin is primarily involved in glucose metabolism and does not directly regulate calcium levels. Thyroid hormones primarily influence metabolism and growth but do not directly control calcium homeostasis. Aldosterone is a hormone produced by the adrenal glands that regulates sodium and potassium levels, rather than calcium. Hence, parathyroid hormone is the clear regulator of calcium levels in the body.