If someone does not take in enough calcium through their diet or does not have enough vitamin D, circulating calcium levels fall and the parathyroid glands produce more parathyroid hormone. It also causes the kidneys to stop calcium being lost in urine as well as stimulating the kidneys to increase vitamin D metabolism (see below). When calcium levels are low, parathyroid hormone is released by the parathyroid glands into the blood and causes the bones to release calcium and increase levels in the bloodstream. The main target organs where parathyroid hormone exerts its effects are the bones and the kidneys. This is important to ensure the nervous system and the body’s muscles can work properly, and also that bones remain strong. Because of this, calcium levels are generally very stable. The parathyroid glands are important in tightly controlling calcium levels in the bloodstream. The parathyroid glands produce a hormone called parathyroid hormone. What hormones do my parathyroid glands produce? Most people have four parathyroid glands, with two parathyroid glands lying behind each 'wing' of the thyroid gland.

The parathyroid glands are small pea-sized glands located in the neck just behind the butterfly-shaped thyroid gland. The parathyroid glands (light pink) produce parathyroid hormone, which increases levels of calcium in the blood. The parathyroid glands lie just behind the thyroid glands in the neck.

Renal glands produce