A person is having problems with calcium metabolism in his body. Which one of the following glands may not be functioning properly?
Parathyroid
Parathyroid hormone (PTH, also known as parathormone) is a peptide hormone, secreted by the parathyroid gland that takes part in the control of calcium and phosphorus homeostasis, as well as bone physiology. PTH is synthesized and released in response to falling levels of Ca++ in the blood. A normal blood Ca++ is important for the functioning of muscles, including the heart, and for the proper functioning of the nervous and endocrine systems. PTH stimulates the osteoclasts (bone cells) in the bone to dissolve the calcium phosphate crystals of the bone matrix and release Ca++ into the blood. PTH also stimulates the kidneys to reabsorb Ca++ from the urine and leads to the activation of vitamin D, needed for the absorption of Ca++ from food in the intestine. Thus any malfunctioning of the parathyroid gland results in problems with calcium metabolism.
The thyroid gland secretes another peptide hormone, calcitonin, that works to lower the blood calcium (Ca++) levels.