Which gland is located behind the thyroid and secretes hormones to maintain calcium levels?

The parathyroid gland, which is located behind the thyroid gland, plays a crucial role in regulating calcium levels in the body. It achieves this through the secretion of parathyroid hormone (PTH), which increases calcium levels in the blood when they are low. This regulation of calcium is essential for various bodily functions, including muscle contraction, nerve function, and bone health.

While the thyroid gland is located in the same region, it primarily regulates metabolism and does not play a direct role in calcium homeostasis. The pineal gland and adrenal gland, while important for other functions, are not involved in calcium regulation. The parathyroid glands specifically respond to changes in blood calcium levels and maintain homeostasis, making them the correct choice for this question.