The body needs charged minerals, called electrolytes, in a narrow range for good health. Sodium, potassium, magnesium, calcium, chloride and phosphate are all electrolytes. They are found in the fluids, blood and tissues of the body. Electrolytes help distribute fluid, signal cells, produce electrical currents and aid in chemical reactions. Calcium is especially important for signaling in nerves and muscles; excess calcium causes problems with nerve and muscle tissue.
Physiology
Calcium is brought into the body in foods. The small intestine absorbs about 40 percent of ingested calcium. The absorption of calcium in the first part of the small intestine, called the duodenum, is dependent on vitamin D. Some calcium is lost in the feces, and some is excreted by the kidneys. The kidneys play an important role in calcium regulation, as they regulate how much calcium stays in the blood versus that which is excreted in the urine. Bone serves as a reservoir for calcium. Parathyroid hormone stimulates the kidneys to conserve calcium and bone to release calcium into the blood. Calcitonin signals bone to keep calcium out of the blood.
Causes
The causes of high calcium generally are problems involving the intestines, bone, kidneys or the hormones that signal them. For example, excessive vitamin D, high parathyroid hormone, drugs affecting the kidney's handling of calcium and bone disorders, including cancers, can cause high calcium. According to "Harrison's Principles of Internal Medicine," the most common cause of high calcium in outpatient clinics is hyperparathyroidism, and the most common cause in hospitalized patients is cancer.
Symptoms
The symptoms of high calcium are a product of the adverse effect on nerve and muscle. The smooth muscle in the intestines is weakened, leading to constipation. Problems in the central nervous system can lead to depression, irritability, confusion, and if the level is very high, coma. Calcium deposits can cause kidney stones. Bone pain can also occur. Generalized fatigue and weakness may also occur, as well as problems with the heart. (See Reference 1, 2 and 3)
Diagnosis and Treatment
The diagnosis of high calcium is established upon laboratory measurement of a sample of blood. However, clues to the diagnosis include a history of symptoms and increased reflex responses. The treatment involves slowly lowering the calcium with intravenous fluids. This is followed by medications that cause the kidneys to increase calcium and urine excretion. Medications, such as bisphosphonates and calcitonin, can also be given. However, definitive treatment usually involves addressing the underlying condition.
References
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci, et al.; 17th Ed 2008
- "Robbins and Cotran Pathologic Basis of Disease"; Vinay Kumar, et al.; 8th Ed 2009
- "Physiology"; Linda S.Costanzo; 4th Ed 2008
- "Henry's Clinical Diagnosis and Management by Laboratory Methods"; Richard A. McPherson, et al.; 21st Ed 2006
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