Overview

Hypercalcemia is a condition in which the calcium level in the blood becomes too high. Too much calcium in the blood can weaken bones and create kidney stones. It also can affect the heart and brain.

Most often, hypercalcemia happens after one or more of the parathyroid glands make too much hormone. These four tiny glands are in the neck, near the thyroid gland. Other causes of hypercalcemia include cancer, certain other medical conditions and some medicines. Taking too much of calcium and vitamin D supplements also can cause hypercalcemia.

Some people have no symptoms of this condition. Others have symptoms that range from mild to serious. Treatment depends on the cause.

Symptoms

You might not have any symptoms if your hypercalcemia is mild. If it's more serious, your symptoms are related to the parts of your body affected by high blood calcium levels. Examples include:

  • Kidneys. Excess calcium makes the kidneys work harder to filter it. This can cause serious thirst and frequent urination.
  • Digestive system. Hypercalcemia can cause stomach upset or pain, vomiting, and constipation.
  • Bones and muscles. Most often, the extra calcium in the blood is leached from the bones. This weakens the bones. It can cause bone pain and muscle weakness.
  • Brain. Hypercalcemia can affect how the brain works. That can lead to trouble focusing, confusion, drowsiness and fatigue. It also can cause depression.
  • Heart. Rarely, serious hypercalcemia can affect the heart. It can cause feelings of a fast-beating, fluttering or pounding heart. It also can cause the heart to beat out of rhythm. It's linked with other heart-related conditions as well.

When to see a doctor

Call your healthcare professional if you think you have any symptoms of hypercalcemia. These can include extreme thirst, frequent urination and pain in the stomach area.

Causes

Calcium helps build strong bones and teeth. It also helps muscles contract and nerves send signals. When the parathyroid glands work right, they release hormones that help maintain the right balance of calcium in the blood. Parathyroid hormones trigger:

  • Bones to release calcium into the blood.
  • The digestive tract to absorb more calcium.
  • The kidneys to release less calcium and activate more vitamin D. Vitamin D plays a key role in the body's ability to absorb calcium.

This delicate balance between too little calcium in the blood and hypercalcemia can be affected by various factors. Hypercalcemia can be caused by:

  • Overactive parathyroid glands. This also is called hyperparathyroidism. It's the most common cause of hypercalcemia. Overactive parathyroid glands make too much parathyroid hormone. The condition can stem from a small tumor that isn't cancer. It also can stem from one or more of the four parathyroid glands becoming larger.
  • Cancer. Lung cancer, breast cancer and some blood cancers can raise the risk of hypercalcemia. Cancer that spreads to the bones also raises the risk.
  • Other diseases. Conditions such as tuberculosis and sarcoidosis can raise blood levels of vitamin D. That in turn spurs the digestive tract to absorb more calcium.
  • Genetic factors. A rare genetic condition called familial hypocalciuric hypercalcemia causes an increase of calcium in the blood. This condition doesn't cause symptoms or complications of hypercalcemia.
  • Little or no movement. People who have a condition that causes them to spend a lot of time sitting or lying down can get hypercalcemia. Over time, bones that don't bear weight release calcium into the blood.
  • Serious dehydration. This is a common cause of mild or short-term hypercalcemia. Having less fluid in the blood causes a rise in calcium.
  • Some medicines. Medicines such as lithium and thiazide diuretics might cause more parathyroid hormone to be released.
  • Supplements. Taking too much calcium or vitamin D supplements over time can raise calcium levels in the blood.

Complications

Hypercalcemia can lead to medical conditions that include:

  • Osteoporosis. This condition involves thinning bones. It could develop if the bones keep releasing calcium into the blood. Osteoporosis can lead to broken bones, curving of the spinal column and loss of height.
  • Kidney stones. If the urine contains too much calcium, crystals might form in the kidneys. Over time, the crystals can combine to form kidney stones. Passing a stone can be very painful.
  • Kidney failure. This condition limits the kidneys' ability to clean the blood and get rid of extra fluid. It can develop over time as hypercalcemia damages the kidneys.
  • Nervous system conditions. Serious hypercalcemia can lead to confusion, dementia and coma. Coma can be fatal.
  • Irregular heart rhythm. This also is called arrhythmia. Hypercalcemia can affect the electrical signals that control the heartbeat. That can cause the heart to beat out of rhythm.
By Mayo Clinic Staff