Hypercalcemia (High Calcium Levels)
Calcium is an important nutrient in our body. It’s needed to help keep our bones, teeth, and tissues strong. But sometimes calcium levels can get too high. This is called hypercalcemia.
What is hypercalcemia?
Hypercalcemia means the calcium levels in your blood are high. This can happen when someone has cancer, especially if the cancer is advanced. You may hear this called hypercalcemia of malignancy.
Hypercalcemia can happen when cancer spreads to the bones (bone metastasis or bone mets). When it spreads, the cancer can push extra calcium into the bloodstream causing high levels of calcium.
Hypercalcemia can also happen in certain types of cancer like lymphoma. Some lymphomas can make the body produce high levels of vitamin D in the body, which can cause high calcium levels.
Why is calcium important?
Besides keeping our bones, teeth, and tissues strong, calcium also helps:
- Muscles to move (including your heart muscle)
- Nerves to send messages through your body
- Blood to clot when you get an injury
The body needs the right amount of calcium to do these jobs and to keep your heart and kidneys working normally.
- When calcium is too low, your heart might not beat as strong or as steady as usual.
- When calcium is too high, it puts extra stress on the kidneys and can lead to complications.
What cancers can cause hypercalcemia?
Cancers that may cause high blood calcium levels are:
- Lung cancer
- Head and neck cancers
- Multiple myeloma
- Leukemia
- Lymphoma
- Kidney cancer
- Breast cancer
- Gastrointestinal (GI) cancers
Symptoms of hypercalcemia
High calcium levels can lead to a variety of symptoms — some mild, some more serious. Recognizing the signs and symptoms early can help you get the care you need.
Signs and symptoms of hypercalcemia include:
- Constipation
- Belly pain
- Passing urine often
- Feeling sluggish or sleepy
- Feeling thirsty all of the time and drinking lots of liquids
- Muscle weakness
- Muscle and joint aches
- Confusion or difficulty thinking
- Seizures
- Irregular heartbeat (palpitations)
- Heart attack
- Passing out
- Poor kidney function
- Kidney failure
- Coma
How is hypercalcemia diagnosed?
Your doctor will order blood tests to check your calcium levels. They may also check your kidney function levels. To confirm a high calcium level, an ionized calcium level may be ordered. You may also need other lab tests, depending on your specific situation.
Early diagnosis is important, because hypercalcemia can be life-threatening if not caught early and treated.
Treatments for hypercalcemia
Treatment for hypercalcemia can include:
- Large amounts of intravenous (IV) fluids to protect the kidneys
- Medicines like bisphosphonates (pamidronate or Aredia and zoledronic acid or Zometa), bone-targeted agent denosumab (Xgeva), or Calcitonin to bring blood calcium levels down quickly
- Dialysis if your kidneys fail
Once the calcium level is back to normal, treating the cancer can help keep the calcium level from getting too high again. You and your cancer care team will discuss what the best options for you.
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- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
American Society of Clinical Oncology. High calcium levels or hypercalcemia. Cancer.net. Content is no longer available.
Horwitz, MJ. Hypercalcemia of malignancy: Mechanisms. UpToDate. Updated May 2024. Accessed at https://www.uptodate.com/contents/hypercalcemia-of-malignancy-mechanisms on July 24, 2025.
National Institute of Health (NIH) Office of Dietary Supplements. Calcium fact sheet for health professionals. Health Information. Updated July 11, 2025. Accessed at https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/ on July 24, 2025.
Shane, E. Clinical manifestations of hypercalcemia. UpToDate. Updated August 2024. Accessed at https://www.uptodate.com/contents/clinical-manifestations-of-hypercalcemia on July 24, 2025.
Shane, E. Diagnostic approach to hypercalcemia. UpToDate. Updated March 2025. Accessed at https://www.uptodate.com/contents/diagnostic-approach-to-hypercalcemia on July 24, 2025.
Shane, E. Etiology of hypercalcemia. UpToDate. Updated August 2024. Accessed at https://www.uptodate.com/contents/etiology-of-hypercalcemia on July 24, 2025.
Shane ,E, Berenson, JR. Treatment of hypercalcemia. UpToDate. Updated May 2024. Accessed at https://www.uptodate.com/contents/treatment-of-hypercalcemia on July 24, 2025.
Last Revised: July 31, 2025
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