Calcium is essential to normal body functions such as bone growth and maintenance, muscle activity and nerve transmission. Much of the calcium in the body is deposited in bone. High blood calcium, or hypercalcemia, occurs when the concentration of calcium in the blood is higher than normal. According to the National Institutes of Health, hypercalcemia is relatively rare in the general population and can be detected with modern tests.
Measurement
Calcium is measured with a simple blood test, and the results are usually available soon after the blood is sampled. Because much of the calcium in the blood is bound to proteins, patients with disorders that cause high or low blood protein may require retesting to obtain a corrected calcium level. It is not necessary to measure routine calcium levels in healthy patients; such testing is reserved for those in whom a calcium disorder is suspected.
Symptoms
Patients with hypercalcemia may have no symptoms at all. Those with symptoms may experience nausea, vomiting, constipation, anxiety, depression, muscle weakness and fatigue. According to MayoClinic.com, the severity of symptoms does not directly correlate with the level of calcium in the blood. Thus, patients with very mild symptoms may have dangerously high calcium levels. Without treatment, longstanding high blood calcium can lead to heart, kidney and bone disease.
Causes
There are many causes of hypercalcemia. However, in a 2007 article in the American Journal of the Medical Sciences, Dr. Michelle Shepard says the majority of cases of hypercalcemia are caused by either hyperparathyroidism or cancer. In hyperparathyroidism, excess hormone secreted from the parathyroid gland causes the bone to release calcium into the blood. In certain cancer patients, the cancer stimulates bone to break down and release calcium. According to Shepard, other important causes of hypercalcemia include excess vitamin D or calcium intake, medication side effects, kidney failure, disorders of the adrenal gland and certain genetic diseases.
Treatment
The treatment of hypercalcemia depends on the underlying cause. Only a medical professional can appropriately determine the correct course of treatment. Sometimes the calcium levels can simply be monitored over time. For persistent or severe hypercalcemia, medications that decrease calcium levels are available, as are drugs that prevent the release of excess calcium from bone. Patients with a disease resulting in hypercalcemia may require treatment of that disease to bring blood calcium levels back to normal. Those with hyperparathyroidism may need surgery to remove the abnormal parathyroid glands.
Prevention
In general, it is not possible to prevent the development of hypercalcemia. This is because most causes of hypercalcemia are diseases that are not related to modifiable factors. For patients taking calcium or vitamin D supplementation, hypercalcemia can be prevented by taking no more than the recommended supplemental doses.
References
- National Institutes of Health: Hypercalcemia
- MayoClinic.com: Hypercalcemia
- "The American Journal of the Medical Sciences"; Michelle Shepard and Jeffrey Smith; 2007
