Overview
Multiple myeloma is a blood cancer that forms in plasma cells, a type of white blood cell. Healthy plasma cells make proteins called antibodies. Antibodies work with other parts of the immune system to help protect the body from germs.
In multiple myeloma, cancerous plasma cells build up in bone marrow. The bone marrow is the soft, spongy tissue inside most bones where blood cells are made.
Myeloma cells make proteins that are not typical. These proteins are called monoclonal proteins, also known as M proteins. These proteins can build up and damage organs, such as the kidneys.
Multiple myeloma is generally preceded by a condition called monoclonal gammopathy of undetermined significance (MGUS). In MGUS, the amount of monoclonal protein is low, and the plasma cell condition doesn't cause myeloma-related organ damage. Most people with MGUS don't develop multiple myeloma.
Multiple myeloma, leukemia and lymphoma are blood cancers, but they start in different tissues or cells. Multiple myeloma starts in plasma cells. Leukemia happens when white blood cells that are not usual grow in excess and don't work as they typically do in blood-forming tissues such as bone marrow. Lymphoma starts in immune cells called lymphocytes.
Treatment can help control multiple myeloma, reduce complications and ease symptoms. It may help people live longer.
Types
Active multiple myeloma
Active multiple myeloma is diagnosed when testing shows a plasma cell condition and at least one myeloma-defining event. These events include myeloma-related organ damage or certain test findings that show a high risk of organ damage. Active multiple myeloma generally needs treatment.
Smoldering multiple myeloma
In smoldering multiple myeloma, blood or bone marrow test results show a plasma cell condition, but there is no myeloma-defining event. The condition hasn't caused organ damage or bone lesions. Most people are monitored instead of being treated right away. People with high-risk smoldering multiple myeloma may be offered treatment.
Dr. Rafael Fonseca, hematologist and Chief Innovation Officer at Mayo
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Symptoms
Some people with multiple myeloma have no symptoms at first. Symptoms may include:
- Bone pain, especially in the back, chest or hips.
- Weak or easily broken bones.
- Tiredness.
- Frequent infections.
- Shortness of breath.
Multiple myeloma can cause a high level of calcium in the blood, called hypercalcemia. Symptoms of high calcium can include:
- Nausea.
- Constipation.
- Loss of appetite.
- Confusion or trouble thinking clearly.
- Weakness.
- Feeling very thirsty.
- Needing to urinate often.
When to see a doctor
Make an appointment with a doctor or other healthcare professional if you have any of these symptoms or other symptoms that worry you.
Causes
It's not clear what causes multiple myeloma.
The disease develops through several changes in plasma cells and in the bone marrow. These changes allow myeloma cells to survive and build up in the bone marrow.
Multiple myeloma involves genetic changes in cancer cells. Having a close family member with multiple myeloma or a related plasma cell condition also raises the risk of developing the disease. But the disease doesn't follow one simple inherited pattern.
Risk factors
Many factors can raise the risk of multiple myeloma.
- Age. The risk of multiple myeloma goes up with age. The median age at diagnosis is about 65.
- Sex at birth. Men are more likely to develop the disease than are women.
- Race. In the United States, Black people are more likely to develop multiple myeloma than white people.
- Family history of multiple myeloma. Having a sibling or parent with multiple myeloma raises the risk of having the disease.
- MGUS. Having MGUS raises the risk of multiple myeloma. But most people with MGUS do not get multiple myeloma.
Complications
Complications of multiple myeloma include:
- Infections. Multiple myeloma can make it harder for the immune system to fight bacterial and viral infections.
- Bone issues. Multiple myeloma can cause bone pain, thinning bones and broken bones.
- Kidney issues. Multiple myeloma may damage the kidneys and may lead to kidney failure.
- Anemia and other blood cell conditions. Myeloma cells interfere with blood cell production in the bone marrow. This can cause a low red blood cell count, called anemia.
Prevention
No lifestyle or environmental change is known to prevent multiple myeloma. Because no direct cause has been found, a diagnosis doesn't mean you did anything to cause it.
Aug. 22, 2026