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, which are 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 on one of the glands. (Most of the time, these growths are not cancerous).
Other conditions can also cause hypercalcemia:
An inherited condition that affects the body's ability to regulate calcium (familial hypocalciuric hypercalcemia)
Being bed-bound (or not being able to move) for a long period of time (this occurs most often in young people)
Calcium excess in the diet. This is called milk-alkali syndrome. It is most often due to at least 2,000 milligrams of calcium per day. Taking too much vitamin D may add to the problem.
Treatment is aimed at the cause of hypercalcemia whenever possible. People with primary hyperparathyroidism (PHPT) may need surgery to remove the abnormal parathyroid gland. This will cure the hypercalcemia.
People with mild hypercalcemia may be able to monitor the condition closely over time.
Severe hypercalcemia that causes symptoms and requires a hospital stay may be treated with the following:
Diuretic medication, such as furosemide
Drugs that stop bone breakdown and absorption by the body, such as pamidronate or etidronate (bisphosphonates)
Fluids through a vein (intravenous fluids) - this is the most important therapy
How well you do depends on the cause of hypercalcemia. The outlook is good for people with mild hyperparathyroidism or hypercalcemia with a treatable cause. Most of the time, there are no complications.
Patients with hypercalcemia due to conditions such as cancer or granulomatous disease may not do well. This is most often due to the disease itself, rather than the hypercalcemia.
Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.