Increased blood calcium, also called hypercalcemia, often occurs in postmenopausal women, but there are a variety of other causes as well. Hypercalcemia can affect bodily processes that rely on calcium, such as bone formation, the release of hormones, muscle contraction, and brain and nerve function. It can also result in muscle weakness and abdominal pain, according to MayoClinic.com.
Primary Hyperparathyroidism
Primary hyperparathyroidism is the most common cause of hypercalcemia, according to MedlinePlus Medical Encyclopedia, a service of the U.S. National Library of Medicine at the National Institutes of Health. The parathyroid glands make parathyroid hormone, which helps regulate the body's blood calcium levels. In primary hyperparathyroidism, too much parathyroid hormone is released, usually due to an enlarged parathyroid gland or from a growth on a gland, causing increased blood calcium.
Cancer
Occurring in 10 to 20 percent of people with cancer, hypercalcemia most often appears in breast and lung cancer as well as some blood cancers, such as multiple myeloma. The symptoms of hypercalcemia can appear gradually and may be similar to symptoms of many cancers and other diseases, according to the National Cancer Institute.
Granulomatous Disease
Granulomatous diseases, such as tuberculosis or sarcoidosis, cause inflammation, which can increase vitamin D blood levels. This in turn stimulates the digestive tract to absorb more calcium, which leads to increased blood calcium, according to MayoClinic.com.
Excess Vitamin D or Calcium Intake
Vitamin D is made by the body after the skin is exposed to sunlight, or it can also be obtained through the diet. Consuming excessive amounts of vitamin D or calcium--at least 2,000 mg daily--can increase blood calcium, according to MedlinePlus.
Medication
Various medications can lead to hypercalcemia. For example, lithium, a drug used to treat bipolar disorder, can increase the release of parathyroid hormone, resulting in hypercalcemia. Thiazide diuretics, medications used to decrease excess body fluid, can also increase blood calcium because less calcium excreted in the urine, according to MayoClinic.com.
Dehydration
Dehydration can cause mild, temporary hypercalcemia, because less fluid in the blood causes an increased concentration of blood calcium, according to MayoClinic.com.
Bedrest
Another cause of hypercalcemia is inactivity or bedrest. Bones that don't bear weight tend to release calcium into the blood, notes MayoClinic.com.
