Causes for High Calcium in Blood

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Hypercalcemia, or elevated calcium levels in the blood, is an electrolyte imbalance that can cause muscle twitching, changes in mood, fatigue and heart rhythm abnormalities. Left untreated, this condition can be fatal. Determining the cause of a patient's hypercalcemia can help medical professionals develop an effective treatment plan that will restore the amount of calcium in the blood to normal levels.


Hyperparathyroidism is one of the most common causes of high calcium in the blood. This condition results from hyperactivity of the parathyroid glands. These glands secrete parathyroid hormone, which works to increase the amount of calcium in the blood. When the parathyroid glands are hyperactive, they secrete excess parathyroid hormone, which causes elevations of serum calcium.

Cancer With Bone Metastases

The Merck Manual for Healthcare Professionals indicates that cancer is one of the major causes of high calcium in the blood. Cancer with bone metastases causes the bones to break down and release their minerals into the blood. Calcium is released from the bones, elevating the concentrations of the mineral in the blood. Cancers that cause high calcium levels include leukemia, carcinoma, multiple myeloma and lymphoma.

Vitamin Toxicity

Information from the American Academy of Family Physicians indicates that high blood calcium can be caused by vitamin toxicity. Vitamin D is necessary for bone development, but it also improves the absorption of calcium from the digestive system. When too much vitamin D is taken, calcium absorption is increased and the level of calcium in the blood becomes elevated. Vitamin A toxicity has also been linked to the development of high calcium in the blood.


According to the Merck Manual for Healthcare Professionals, people who are immobilized may develop high levels of calcium in the blood because of the breakdown of bone that occurs. Immobilization may be due to paraplegia, quadriplegia, orthopedic casts or traction, or osteoporosis. Paget's disease of the bone may also cause the breakdown of bones and the release of minerals into the bloodstream.

Granulomatous Diseases

According to the National Institutes of Health, granulomatous diseases are a group of diseases that make it difficult for immune cells to kill pathogens. Physicians from the Cleveland Clinic indicate that most granulomatous diseases can cause elevation of the calcium levels in the blood. Examples of granulomatous diseases that cause elevated calcium levels include tuberculosis, candidiasis, histiocytosis, sarcoidosis and Crohn's disease. High calcium in the blood occurs because these diseases cause elevated calcitriol levels.

Endocrine Dysfunction

The Merck Manual for Healthcare Professionals indicates that several endocrine disorders can cause high levels of calcium in the blood. These disorders affect the production of several hormones related to the regulation of calcium. Examples of endocrine disorders that cause high levels of calcium in the blood include Cushing's disease and Addison's disease.


Some prescription drugs can lead to elevated calcium levels. According to physicians from the Cleveland Clinic, lithium and thiazide diuretics increase the amount of calcium in the blood. Lithium therapy causes mild elevations that usually resolve once therapy has been discontinued. Thiazide diuretics can cause increased blood calcium levels because they decrease the excretion of calcium by the kidneys.