Hypercalcemia and Cancer

by National Cancer Institute

Hypercalcemia occurs in 10%-20% of people with cancer, although it occurs much less often in children. The cancers most often associated with hypercalcemia are cancer of the breast and lung, as well as certain cancers of the blood, particularly multiple myeloma. Early diagnosis and treatment with fluids and drugs that lower calcium levels in the blood can improve symptoms in a few days, but diagnosis may be difficult. Symptoms of hypercalcemia can appear gradually and may resemble symptoms of many cancers and other diseases. Early diagnosis and treatment are not only lifesaving in the short term, but may also increase the patient's ability to complete cancer therapy and improve the patient's quality of life.

Patients who have advanced terminal cancer and are no longer receiving treatment for the cancer may choose not to be treated for hypercalcemia. This option should be considered by a patient and his or her family in advance, before symptoms of hypercalcemia occur.

Normal calcium regulation

Healthy people consume about the same amount of calcium in their diet as their bodies lose in urine, feces, and sweat. Hypercalcemia associated with cancer disrupts the body's ability to maintain a normal level of calcium.

Kidney function

Normal, healthy kidneys are able to filter large amounts of calcium from the blood, excrete the excess not needed by the body, and retain the amount of calcium the body does need. However, hypercalcemia may cause such high levels of calcium in the body that the kidneys are overworked and become unable to excrete the excess. Some tumors produce a substance that can cause the kidneys to excrete too little calcium. This results in a large amount of urine being produced, which then causes dehydration. Dehydration may lead to appetite loss, nausea, and vomiting which make the dehydration worse. Inactivity caused by weakness and tiredness may increase the amount of calcium in the blood by increasing the amount of calcium that is absorbed from the bones. Calcium deposits may collect in the kidneys, causing permanent damage.

Causes of Hypercalcemia

The main causes of hypercalcemia due to cancer are an increase in the amount of calcium absorbed from the bones, and an inability of the kidneys to excrete excess calcium. Some cancer cells secrete substances that cause calcium to be absorbed into the bloodstream from bones. Immobility, dehydration, anorexia, nausea, and vomiting may also increase calcium levels.

Incidence

Hypercalcemia occurs most frequently in patients with lung and breast cancer. It may also occur in patients with multiple myeloma, head and neck cancer, cancer of unknown primary origin, lymphoma, leukemia, kidney cancer, and gastrointestinal cancer.

Symptoms

There is little relationship between symptoms of hypercalcemia and the actual level of calcium in the blood. Symptoms of hypercalcemia resemble symptoms of other illnesses, making an early and rapid diagnosis difficult. The severity of the symptoms may depend on other factors, such as previous cancer treatment, reactions to drugs, or other illnesses a patient may have.

Most patients do not experience all of the symptoms of hypercalcemia, and some patients may not have any symptoms at all. However, most patients with high calcium levels in the blood do have symptoms. Some patients develop signs of hypercalcemia when calcium levels are only slightly high, while patients who have had higher calcium levels for a long time may show few symptoms.

The most common symptoms of hypercalcemia are feeling tired, difficulty thinking clearly, lack of appetite, pain, frequent urination, increased thirst, constipation, nausea, and vomiting.

Symptoms may be classified by the affected body part:

Nervous system

Calcium plays a major role in the normal functioning of the central nervous system (the brain and spinal cord). Symptoms of hypercalcemia may include weakness, loss of reflexes in the muscles, and decreased stamina. Patients with central nervous system symptoms may have changes in personality, difficulty thinking or speaking clearly, disorientation, or hallucinations. Eventually, coma may result. Headaches can also occur, which can be made worse by vomiting and dehydration.

Heart

Hypercalcemia affects normal heart rhythms and increases sensitivity to some heart medications (such as digoxin). As calcium levels increase, irregular heartbeats may develop, and may lead to a heart attack.

Gastrointestinal

Increased stomach acid often is produced with hypercalcemia and may intensify loss of appetite, nausea, and vomiting. Constipation may result from the dehydration associated with hypercalcemia.

Kidney

Hypercalcemia causes the kidneys to not function correctly, leading to the production of large volumes of urine. The large amount of urine combined with less liquid intake leads to symptoms of dehydration, including thirst, dry mouth, little or no sweating, and concentrated urine. Patients with myeloma often have kidney problems due to hypercalcemia. Kidney stones may result from long-term hypercalcemia.

Bone

Hypercalcemia of cancer can result from bone metastases or bone loss, and may contribute to broken bones, bone disfigurement, and pain.

Assessment

Laboratory assessment

A blood test is done to check the level of calcium. Other blood tests may be done to check kidney function.

Clinical assessment

Patients with high calcium levels should be examined for the following:

Symptoms:

• Nerves and muscles (muscle strength, muscle tone, reflexes, tiredness, indifference, depression, confusion, restlessness).
• Heart (high blood pressure, heart changes, irregular heartbeat, digitalis poisoning).
• Kidneys (production of too much urine, night-time urinating, sugar in the urine, excess thirst).
• Gastrointestinal (loss of appetite, nausea, abdominal pain, constipation, abdominal bloating).
• Other (muscle and bone pain, itching).

History:

• How fast did the symptoms appear?
• Is there x-ray evidence of primary or metastatic bone disease?
• Has the patient been taking tamoxifen, estrogen, or androgens?
• Is the patient taking digoxin?
• Is the patient receiving calcium in intravenous fluids?
• Is the patient receiving thiazide diuretics, vitamins A or D, or lithium?
• Is there another disease present that could cause dehydration or lack of movement?
• Are there effective treatments for the patient's cancer?

Decision to treat

The decision to treat hypercalcemia depends on the treatment goals determined by the patient, caregivers, and the physician. The natural course of untreated hypercalcemia progresses to loss of consciousness and coma. This may be preferred by some patients at the end of life who have unrelieved suffering and/or untreatable symptoms.

About the Author

www.nci.nih.gov
The National Cancer Institute's research programs are extensive and contain many innovative initiatives. I invite you to explore our Web site to find out more about the exciting work being conducted here at NCI and by NCI-supported scientists throughout the country.