Certain types of cancer and types of treatment may cause symptoms of hypercalcemia.

Some cancer cells cause the kidneys to return calcium to the blood after filtering it, instead of passing the extra calcium out of the body in urine. The kidneys keep making urine as they try to get rid of the extra calcium, and this causes the body to be dehydrated (not enough fluid). Dehydration can lead to the following:

• Loss of appetite.
• Nausea.
• Vomiting.

Cancer patients are often too tired and weak to be as active as usual. Being inactive can increase calcium in the blood because bones release calcium when they are not being used. Also, some blood cancers make substances that cause bone to break down and release calcium into the blood.

Certain types of biologic therapy used for cancer treatment can also cause hypercalcemia. These therapies include the following:

• Growth factors.
• Interleukins.
• Tumor necrosis factors.

Hormone therapy can also increase the amount of calcium in the blood.

Different patients may have different symptoms.

Hypercalcemia symptoms may differ between patients. They can appear slowly over time and may look like symptoms of cancer and other diseases. The most common symptoms of hypercalcemia include the following:

• Feeling tired.
• Trouble thinking clearly.
• Loss of appetite.
• Pain.
• Frequent urination.
• Increased thirst.
• Constipation.
• Nausea.
• Vomiting.

Hypercalcemia symptoms also depend on the organs that are affected.

Hypercalcemia can affect many organs of the body and symptoms depend on which organs are affected.

Neurologic symptoms

Calcium plays a major role in the way the central nervous system (the brain and spinal cord) works. Nervous system symptoms of hypercalcemia include the following:

• Weakness.
• Loss of reflexes.
• Headaches, which can become worse by vomiting and dehydration.
• Coma.
• Mental problems, such as:
  • Personality changes.
  • Trouble thinking or speaking clearly.
  • Confusion about time or place.
  • Hallucinations.

Sometimes mental problems need treatment separate from the treatment for hypercalcemia.

Heart symptoms

Hypercalcemia affects normal heart rhythms. It can also make the heart more sensitive to certain heart medicines (such as digoxin). Calcium levels that are higher than normal can cause irregular heartbeats or a heart attack.

Gastrointestinal symptoms

Increased stomach acid often occurs with hypercalcemia and may make the following symptoms worse:

• Loss of appetite.
• Nausea.
• Vomiting.

Constipation may become worse if you are not drinking enough fluids.

Kidney symptoms

Hypercalcemia causes the kidneys to make too much urine. This loss of fluid may lead to dehydration, which causes the following symptoms:

• Thirst.
• Dry mouth.
• Little or no sweating.
• Dark yellow urine.
• Poor elasticity (skin does not spring back in place when pulled up and released).

Patients with multiple myeloma often have kidney problems because of hypercalcemia. Kidney stones may form if hypercalcemia lasts a long time.

Bone symptoms

Hypercalcemia can be caused by cancer spreading to the bone or by bone loss. Bones may be painful or break.

Check NCI’s list of cancer clinical trials for U.S. supportive and palliative care trials about hypercalcemia that are now accepting participants. The list of trials can be further narrowed by location, drug, intervention, and other criteria.

General information about clinical trials is also available from the NCI Web site.