According to the Merck Manuals Online Medical Library, the body contains two types of blood calcium--bound and unbound. Bound calcium is attached to proteins in the blood and serves no function in the body. Approximately 40 percent of the calcium in blood is bound. Unbound calcium moves independently in the blood and affects the body's functions. Decreased blood calcium, also called hypocalcemia, refers to low levels of unbound calcium.
Functions of Calcium
One of the most important functions of calcium in the body is to build strong bones and teeth. Calcium pairs with phosphorous to provide structure to the bones, which gives them strength. Approximately 99 percent of the body's calcium is located in the bones, according to "Nutrition and You" by Joan Salge Blake The calcium located in the blood is responsible for proper muscle contraction, dilation and contraction of blood vessels, blood clotting and transmission of nerve signals.
Causes
Blood calcium levels decrease when excess calcium is excreted in the urine or when calcium does not successfully travel from the bones into the bloodstream. One of the most common causes of hypocalcemia is hypoparathyroidism, which is decreased functioning of the parathyroid glands, according to Cleveland Clinic. The parathyroid glands release a hormone called parathyroid hormone that controls blood calcium levels. Without adequate parathyroid hormone, blood calcium levels can drop significantly. Other possible causes of decreased blood calcium include vitamin D deficiency, kidney abnormalities, inadequate dietary intake of calcium, low levels of magnesium, pancreatitis and certain medications.
Symptoms
The condition can range from extremely mild to life-threatening, depending on how low the calcium levels in the blood become. When blood calcium levels are only slightly lower than normal, the condition is usually asymptomatic. As calcium levels drop further, the brain becomes affected and neurological symptoms develop. These symptoms include confusion, loss of memory, depression, hallucinations, tingling in various areas of the body, muscle aches, muscle spasms, seizures and arrhythmias.
Diagnosis
According to the Merck Manuals Online Medical Library, decreased blood calcium levels are often diagnosed before any symptoms begin during routine blood tests. Once decreased blood calcium levels are discovered, more blood tests will be performed to determine the underlying cause of the hypocalcemia.
Treatment
Most cases of asymptomatic hypocalcemia can be successfully treated with oral supplementation of calcium. Once symptoms appear, intravenous administration of calcium becomes necessary. Vitamin D, which helps the body absorb calcium from the digestive tract, is often given in conjunction with calcium.
References
- Merck Manuals Online Medical Library: Calcium: Minerals and Electrolytes
- Cleveland Clinic: Hypocalcemia
- Lab Tests Online: Calcium
- "Nutrition and You"; Joan Salge Blake; 2008
