December 2, 2011
Dear Mayo Clinic:
A recent blood test showed that I have mild hypercalcemia. What could cause this? Is it a serious condition?
When blood contains too much calcium, the condition is called hypercalcemia. Most often, the cause is a problem with the parathyroid glands and the hormone they produce. You should have this condition evaluated further. If left untreated, hypercalcemia can cause a variety of persistent symptoms and can lead to other health problems, including osteoporosis and kidney stones.
The body needs calcium to maintain bones. Calcium also plays an important role in the body's ability to contract muscles, release hormones and ensure that the nerves and brain work properly. High calcium levels in the blood, however, can interfere with these functions.
In some cases, a blood test result that shows mild hypercalcemia can be attributed to dehydration or to a blood sample that was taken when the person was not fasting. Also, eating or drinking foods or supplements with calcium or vitamin D just before a blood test can cause blood calcium levels to rise. If you haven't already done so, have the blood test repeated. If your calcium level is normal in the second test, one of these causes likely was responsible for the first abnormal result, and no treatment is needed.
If a repeat blood test still shows mild hypercalcemia, more investigation is needed. Although many conditions can cause hypercalcemia — including some advanced cancers, other medical disorders, certain medications, and excessive use of calcium and vitamin D supplements — the most common cause in healthy people is primary hyperparathyroidism.
Four parathyroid glands are located in the front of your neck, behind the thyroid gland. Parathyroid glands release parathyroid hormone that controls the level of calcium in the body. Usually when blood calcium levels fall, the parathyroid glands respond by releasing enough parathyroid hormone to return blood calcium to a normal level. The hormone raises calcium levels by triggering the release of calcium from the bones. When blood calcium levels are too high, the parathyroid glands normally produce less of this hormone. But sometimes one or more parathyroid glands produce more hormone than the body needs, leading to hypercalcemia.
Hypercalcemia can cause a variety of symptoms. The most common are fatigue, aches and pain in the muscles and joints, and problems with concentration or memory. If left untreated, hypercalcemia can lead to serious complications. For example, if the bones continue to release calcium into the blood, osteoporosis, a bone-thinning disease, can result. If urine contains too much calcium, crystals may form in the kidneys. Over time, these crystals may combine to form kidney stones.
Hypercalcemia caused by primary hyperparathyroidism may sometimes be successfully managed without surgery. If a person has lost bone mass or developed kidney stones due to excess blood calcium, those conditions can be treated. In most cases, osteoporosis caused by hypercalcemia is reversible after surgical cure of primary hyperparathyroidism. Mild hypercalcemia is sometimes simply observed and the blood calcium is monitored.
Surgery is needed if hypercalcemia caused by hyperparathyroidism becomes severe or cannot be controlled. Typically, only one of the glands is overproducing parathyroid hormone, and a doctor may recommend surgery to remove the affected gland. Prior to surgery, doctors can use a parathyroid scan to identify which gland is involved. After the gland is removed, the remaining parathyroid glands compensate for the missing one, and blood calcium returns to normal.
Talk to your doctor about the steps you should take next to address your abnormal blood calcium test result. In most cases, the cause of mild hypercalcemia can be readily identified and effectively treated.
— Bart Clarke, M.D., Endocrinology, Mayo Clinic, Rochester, Minn.