Hypercalcemia

If the calcium level in your blood is higher than normal, you have a condition called hypercalcemia. Too much calcium in your blood can weaken your bones, cause kidney stones, and affect how your heart and brain work.

If high calcium blood levels are due to cancer, it’s called hypercalcemia of malignancy. Experts estimate that about 30% of people with cancer have this condition, although the numbers may be higher in people with advanced-stage disease. Certain types of cancer, including breast cancer, are more likely to cause hypercalcemia of malignancy. 

Among people diagnosed with breast cancer, hypercalcemia often is seen in people with multiple areas of bone metastases, meaning the cancer has spread to a number of places in the bones. Still, some people without bone metastases also have hypercalcemia. This is because breast cancer can cause the immune system to secrete proteins that lead to the breakdown of bone tissue. If too much bone tissue breaks down, it can increase blood calcium levels.

High calcium levels may or may not be a sign of cancer. It depends on what’s causing the high levels. If your calcium levels are high or you have symptoms of hypercalcemia, your doctor will order tests to figure out why.

Besides cancer, there are a number of other diseases that can cause hypercalcemia, including hyperparathyroidism (one or more overactive parathyroid glands).

Medicines also can cause hypercalcemia. These include diuretics, which are prescribed for high blood pressure, and lithium, which is used to treat bipolar disorder. Taking too many Tums or Rolaids for heartburn also can cause hypercalcemia because these medicines contain calcium carbonate.

In addition, being severely dehydrated or taking too many vitamin D, vitamin A, or calcium supplements can cause hypercalcemia.

Less common causes of hypercalcemia include lung diseases, such as tuberculosis, kidney failure, being bedridden for a long time, and sarcoidosis, a condition that causes your immune system to form lumps in your lungs, lymph nodes, skin, eyes, and other parts of your body.

Hypercalcemia symptoms vary widely from person to person. Some people with mild cases have no symptoms at all, while other people with more serious disease may have more severe signs.

The symptoms you have are related to the area of your body that’s most affected.

If your kidneys are affected, you’ll likely be extremely thirsty and pee more frequently.

If your digestive system is affected, you’ll probably feel abdominal pain or discomfort, loss of appetite, nauseated, and may vomit or be constipated.

If your bones and muscles are affected, you may have bone pain and muscle weakness.

If your brain is affected, you might have fatigue, trouble concentrating and focusing, and depression.

While uncommon, hypercalcemia also may affect the heart. If it does, your heart may beat faster than usual or feel like it’s pounding or fluttering. Hypercalcemia also can cause an abnormal heart rhythm.

If hypercalcemia is caused by overactive parathyroid glands or breast cancer, it may lead to osteoporosis. 

Overactive parathyroid glands release too much parathyroid hormone. This causes your bones to release more calcium into the blood than normal. If your bones release too much calcium, they lose density and are thinner and weaker, which is the definition of osteoporosis.

If breast cancer causes hypercalcemia, it’s usually because breast cancer can make the immune system secrete proteins that make certain bone cells called osteoclasts more active. Osteoclasts break down bone tissue, an important function in the life cycle of bones. If osteoclasts are overactive, it can lead to osteoporosis.

Treatments for hypercalcemia are based on what’s causing the condition. But in almost all cases, your doctor will recommend that you drink plenty of fluids and avoid things that can worsen the condition, such as vitamin D supplements, chewable antacids, or multivitamins with calcium.

If hypercalcemia is caused by breast cancer, treatment is usually an intravenous bisphosphonate, such as zoledronic acid (brand names: Zometa or Reclast) or pamidronate (brand name: Aredia). These treatments usually improve your condition within a few days.

Depending on how severe the hypercalcemia is, your doctor also may recommend an IV infusion of Xgeva (chemical name: denosumab) or a calcitonin injection. Calcitonin is a hormone made by your thyroid gland that makes osteoclasts less active. It also tells your kidneys to get rid of calcium. Calcitonin is also found in salmon and may be called calcitonin salmon.

In some cases, your doctor may recommend steroids or cinacalcet as a treatment. Steroids reduce the breakdown of bone tissue and also lower the amount of calcium absorbed by the intestines. Cinacalcet works by making the parathyroid glands produce less hormone, which reduces blood calcium levels.