Fact Sheet


  • Editors
  • Benjamin Leder, MD
    Shonni J. Silverberg, MD
    Andrew F. Stewart, MD

What is high blood calcium?

People with high blood calcium, also called hypercalcemia, have above-normal levels of calcium in their blood.

Did you know?

Hormone problems are some of the many possible causes of high blood calcium.

Calcium is a mineral found mostly in your bones, where it builds and maintains bone strength. A small amount of calcium is also found in muscle and blood cells, where it plays several important roles:

High blood calcium often does not cause any health problems. But over time, some causes of high blood calcium can lead to osteoporosis (thinning of the bones) and kidney stones. Very high blood calcium can cause more serious problems, including kidney failure, abnormal heart rhythm, mental confusion, and even coma.

How does your body control blood calcium levels?

Normally, your body controls blood calcium by adjusting the levels of several hormones.

When blood calcium levels are low, your parathyroid glands (four pea-sized glands in your neck) secrete a hormone called parathyroid hormone (PTH). PTH helps your bones release calcium into the blood.

Vitamin D is also important in keeping calcium levels in the normal range. Vitamin D, which is actually a hormone, helps your body absorb calcium and move it from your intestines into your blood.

Together, PTH and vitamin D, along with other hormones and minerals, help move calcium in or out of body tissues to keep your blood calcium at a normal level.

Symptoms of high blood calcium

High blood calcium may cause no symptoms (what you feel), or it may cause symptoms such as

  • Muscle weakness
  • Fatigue
  • Constipation
  • Nausea
  • Mood changes
  • Confusion

What causes high blood calcium?

The most common cause of high blood calcium is a condition called primary hyperparathyroidism or PHPT. In this condition, one or more of the parathyroid glands produces too much PTH. This, in turn, causes the bones to release too much calcium into the blood. Women over the age of 50 are more likely than others to have PHPT.

Certain types of cancer, most often breast cancer, lung cancer, or multiple myeloma (a type of blood cancer), can also cause high blood calcium. This usually occurs late in the course of cancer.

Less common causes of hypercalcemia include these health problems:

Other infrequent causes of high blood calcium include

How is high blood calcium diagnosed?

Doctors detect high blood calcium through a blood test that measures calcium levels. To help pinpoint the cause, your health care provider may check PTH and vitamin D levels, as well as kidney function and levels of calcium in your urine. Your provider may do other tests to further assess your condition, such as checking your blood levels of phosphorus (a mineral). Imaging studies also may be helpful, such as bone mineral density, ultrasound, or other types of scans.

How is high blood calcium treated?

Your treatment will depend on the cause of your high blood calcium. In general, the best treatment is to take care of the condition that is causing the high blood calcium. For instance, people with primary hyperparathyroidism who have symptoms usually have surgery to remove the problem-causing parathyroid gland.

Until the underlying problem is resolved, treatment may include medicines to improve blood calcium levels. When blood calcium is dangerously high, people may need treatment in a hospital to return their blood calcium to a safe level.

You might not need any treatment if your blood calcium is only slightly high or you have not developed any health problems. Instead, your health care provider will continue to check your condition over time.

Talk with your health care provider about the best treatment for your condition.

Questions to ask your doctor