Tomas had low calcium levels in his body. Vitamin D is essential for maintaining calcium balance. He began taking vitamin D supplements, which, due to high doses, increased his calcium levels. Which endocrine glands will help maintain homeostasis by regulating this increase in calcium?

The endocrine glands responsible for maintaining calcium homeostasis in the body are the parathyroid glands and the thyroid gland.

1. Parathyroid Glands: These small glands, located behind the thyroid gland, secrete parathyroid hormone (PTH). When calcium levels in the blood drop, the parathyroid glands release PTH, which stimulates the release of calcium from bones into the bloodstream, enhances calcium absorption in the intestines, and increases reabsorption of calcium in the kidneys. This process helps elevate blood calcium levels.
2. Thyroid Gland: Although the thyroid gland primarily regulates metabolism through the secretion of thyroid hormones (T3 and T4), it also plays a role in calcium homeostasis. The thyroid gland secretes calcitonin, a hormone that lowers blood calcium levels by inhibiting calcium release from bones and promoting calcium excretion by the kidneys.

When Tomas took high doses of vitamin D supplements that led to increased calcium levels, these endocrine glands, particularly the parathyroid glands, would play a vital role in maintaining calcium homeostasis. The parathyroid glands would regulate the elevated calcium levels by modulating the release of parathyroid hormone (PTH) to manage calcium levels in the blood and tissues within a normal range.