8 Blood Tests for Multiple Myeloma

Multiple myeloma is a rare cancer of the plasma cells in bone marrow. Plasma cells are a type of infection-fighting cell. Multiple myeloma develops when plasma cells grow uncontrolled and produce large amounts of abnormal proteins. 

Over time, cancerous plasma cells start to “crowd out” healthy cells in the bone marrow. This means there’s less room for blood cells to form. And this leads to symptoms like anemia and frequent infections.

Blood tests can help diagnose multiple myeloma. Common blood tests can help identify whether or not a person needs further testing to see if they have multiple myeloma. 

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Specialized blood tests and other medical tests can confirm whether someone has multiple myeloma. 

Here, we’ll take a look at which common blood tests can show signs of multiple myeloma. And we’ll also cover which specialized blood tests can confirm a diagnosis. 

1. Complete blood count (CBC)

A complete blood count (CBC) measures different types of cells in the blood, including white blood cells, red blood cells, and platelets. People with multiple myeloma often have low levels of some or all of these types of cells. 

A CBC can’t diagnose multiple myeloma. But it can help identify people who need specialized testing to see if they have multiple myeloma or another condition. 

2. Blood calcium level

Calcium is a mineral stored in the bones. People with multiple myeloma develop bone breakdown as the cancerous cells damage bone marrow and surrounding bone tissue. When bone breaks down, it releases calcium into the bloodstream. People with multiple myeloma will have high levels of calcium in the blood. This is called hypercalcemia. 

Not everyone with hypercalcemia has multiple myeloma. But a high calcium level is a sign that people should be checked for multiple myeloma and other medical conditions. 

3. Kidney function tests

Kidney function tests give a picture of the kidneys’ overall health. A creatinine level is part of a kidney function test. 

In multiple myeloma, the abnormal proteins created by the cancer cells are released into the blood and then travel to the kidney. These proteins can damage the kidneys. That damage can show up as a high creatinine level. 

Again, not everyone with a high creatinine level will have multiple myeloma. But a high creatinine level is a sign that you need to be checked for medical conditions that can damage the kidneys. 

4. Lactate dehydrogenase (LDH)

Damaged tissue releases an enzyme into the bloodstream called lactate dehydrogenase (LDH), also called lactic acid dehydrogenase. People with tissue injury caused by multiple myeloma may have high levels of LDH. 

Not everyone with a high LDH level has multiple myeloma. But a high level can raise concern for multiple myeloma. This is especially true if people also have other concerning blood test results, like high calcium levels and unusual CBC results.

5. Quantitative immunoglobulins

Immunoglobulins are a type of protein made by plasma cells. A quantitative immunoglobulin test shows how much of each type of immunoglobulin is in the blood. 

Cancerous plasma cells overproduce certain immunoglobulins. People with multiple myeloma often have unusual or unbalanced patterns in their quantitative immunoglobulin levels. For example, one immunoglobulin level may be much higher than the others. 

A quantitative immunoglobulin test can’t diagnose multiple myeloma on its own. But there are fewer medical conditions that cause an abnormal result. That means there’s a higher chance that multiple myeloma is causing the changes — especially if you also have other abnormal test results. 

6. Serum protein electrophoresis

Serum protein electrophoresis (SPEP) separates immunoglobulins in the blood based on their size and electrical charge. People with multiple myeloma are more likely to have the SPEP showing a high level of an abnormal immunoglobulin called a monoclonal protein. Monoclonal protein is also called “M protein.” And the high level is sometimes referred to as an “M spike.”

An M spike may not be enough to diagnose multiple myeloma. But finding a high level of monoclonal protein is the first step to confirming a diagnosis. More specialized tests can figure out exactly what type of monoclonal protein is being overproduced. This is important for diagnosis and treatment. 

7. Serum free light chain assay

Serum free light chain assay (sFLC assay) is a blood test that measures light chain proteins. Light chain proteins are made by plasma cells. Normally, there should be a balance between light and heavy chains in the body. But cancerous plasma cells make more light protein, throwing off the balance in the body.

An abnormal result can be a sign of multiple myeloma. It’s especially helpful if someone doesn’t have an M spike — but has other blood test results that suggest multiple myeloma. 

8. Beta-2 microglobulin (ß2M)

Beta-2 microglobulin is a tumor maker. The presence of a tumor marker usually indicates that cancer is present somewhere in the body. Beta-2 microglobulin is a tumor marker that accumulates in people who have multiple myeloma and other bone marrow disorders. The presence of beta-2 microglobulin is a sign of multiple myeloma. 

Other diagnostic tests for multiple myeloma

Blood tests alone may not be enough to diagnose multiple myeloma. Other tests you may need to diagnose multiple myeloma include:

• Urine tests: The abnormal proteins made by cancerous plasma cells can spill in the urine. Urine tests like urine protein electrophoresis (UPEP) measure these protein levels and can help diagnose multiple myeloma. 

• Imaging tests: Your healthcare team may ask you to get an imaging test to look for lesions in the bones caused by multiple myeloma. Common imaging tests for multiple myeloma include whole-body CT scans, MRIs, and PET scans.

• Bone marrow biopsy: During a bone marrow biopsy, a sample of the tissue inside the bone is removed for analysis. This test allows the healthcare team to confirm that cancer cells are present in the bone marrow. 

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Written by:

Christine Giordano, MD

Christine Giordano, MD, is board-certified in general internal medicine. She received her medical degree from Rutgers New Jersey Medical School and completed residency at Thomas Jefferson University.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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