Calcium is important to many body functions, including: Nerve
and brain function Parathyroid hormone (PTH) and vitamin D help
manage calcium balance in the body. PTH is made by the
parathyroid glands -- four small glands located in the neck
behind the thyroid gland. Vitamin D is obtained when the skin is
exposed to sunlight, and from dietary sources such as: Fortified
dairy products Primary hyperparathyroidism is the most common
cause of hypercalcemia. It is due to excess PTH release by the
parathyroid glands. This excess occurs due to an enlargement of
one or more of the parathyroid glands, or a growth (usually not
cancer) on one of the glands. Other medical conditions can also
cause hypercalcemia: Hypercalcemia affects less than 1 percent
of the population. The ability to measure blood calcium since
the 1960s has improved detection. Today, the condition is
diagnosed at an early stage so most patients with hypercalcemia
have no symptoms. Women over age 50 are most likely to have
hypercalcemia, usually due to