Multiple myeloma is a cancer of the white blood cells (plasma B cells) found in bone marrow — the spongy tissue found in some bones. In about 50 percent of cases, multiple myeloma is diagnosed by primary care providers. Routine blood and urine tests, for instance, might reveal abnormalities associated with multiple myeloma. If a physician suspects a person has myeloma, they will recommend clinical tests to confirm the diagnosis. These tests can also be used to check the progression of a person’s myeloma during and after treatment.
Here, we will explore some of the lab tests used in multiple myeloma, including how they are used and what they can reveal to your health care team.
Early symptoms of multiple myeloma — including fatigue and back pain — often mimic the symptoms of other diseases and conditions. For this reason, further clinical testing is often needed to confirm a diagnosis of myeloma. Lab tests can also be used to check the stage of myeloma and track its progression during treatment. Imaging tests, for instance, can be used to determine where myeloma is located, how it has progressed, and how well a person is responding to their treatment.
These tests reveal potential signs of myeloma and related disorders. They include:
An elevated total protein may suggest to a doctor that more testing is necessary.
Several lab tests may be used to initiate or confirm a diagnosis of multiple myeloma. A detailed health history is also helpful. The health history of both you and your family may show risk factors associated with multiple myeloma, such as age, gender, race, and obesity. A previous diagnosis of other plasma cell diseases is also a risk factor.
Complete blood count (CBC) is a routine blood test that measures the overall health of your blood. This includes information about kidney function. It also shows if your blood contains abnormal proteins, too much calcium, or too few red blood cells. All of these could indicate multiple myeloma.
Routine urine tests can also detect abnormal proteins, such as M proteins (monoclonal proteins). Protein in the urine requires additional testing to be identified, so your doctor may want you to take a 24-hour urine test to figure out what to do next.
Several additional blood tests beyond the CBC are used to check the levels of albumin, calcium, creatinine, and other electrolytes in your blood. Your doctor will be on the lookout for low levels of albumin and high levels of calcium and creatinine (a hint that kidney function is affected).
Other specific blood tests can be used to both diagnose myeloma and check how far the disease has progressed. Each one measures the levels of different substances in your blood.
Lactic acid is an enzyme that helps your body make energy. A lactic dehydrogenase (LDH) test measures how much lactic acid is in your blood. High levels of LDH in the blood can be an indicator of disease progression.
Quantitative immunoglobulin tests look at the presence of antibodies (immunoglobulins) in the blood. Levels that are too high or to too low may indicate a problem that should be looked at more closely.
Serum protein electrophoresis (SPEP) is another antibody test. Myeloma antibodies are all the same (monoclonal). SPEP measures all of the antibodies in the blood and determines which are monoclonal.
An immunofixation or immunoelectrophoresis test determines exactly what type of abnormal antibodies are present in the blood. Monoclonal antibodies have several names, including monoclonal protein or M protein, M spike, paraprotein, and monoclonal immunoglobulin.
A serum free light chain test looks at chains formed by immunoglobulins. Light and heavy chains can link, or they can be free. Free light chains are the problematic ones. The presence of more free light chains than linked ones indicates a plasma cell disorder, such as multiple myeloma.
This test looks for the presence of the protein beta-2 microglobulin. High levels of this protein are an indicator of disease progression.
Imaging tests for myeloma include X-rays, magnetic resonance imaging (MRI), computerized tomography (CT) scans, and positron emission tomography (PET) scans. Imaging tests are painless, although PET scans involve an injection.
All of these tests help determine the presence, stage, and progression of multiple myeloma. If you are already being treated for multiple myeloma, imaging tests help monitor how your treatment is going and guide your doctor in determining how it will continue.
X-ray images can be used to determine the progression of multiple myeloma and detect bone lesions, which may indicate organ damage caused by abnormal plasma B cells.
CT scans are more sensitive than traditional X-rays. These scans can be used to determine the stage of a person’s myeloma upon diagnosis.
MRI can be used to detect myeloma in its early stages or to determine how advanced it is. The presence of more than one lesion found with MRI may support a diagnosis of myeloma and determine how far the disease has progressed.
PET scans can help determine the extent of multiple myeloma. A particular type of PET scan, fluorodeoxyglucose PET, is highly sensitive and can be used to visualize bone lesions at the time of diagnosis.
Bone marrow biopsy is an important step in diagnosing multiple myeloma. A biopsy is the removal of a sample of tissue. The sample is then sent to a medical laboratory for testing — in this case, testing for myeloma cells and plasma cells. Too many plasma cells indicate multiple myeloma.
Bone marrow biopsies are usually taken from the hip bone. It’s a short procedure, taking around 10 minutes to get both samples. To perform the biopsy, your doctor numbs the back of your pelvic bone, then inserts a needle to remove a small amount of liquid bone marrow (aspiration) and a very small piece of bone for pathology. If myeloma cells are present, the pathologist moves on to the next important assessment, genome sequencing.
For people already undergoing treatment for multiple myeloma, a minimal residual disease (MRD) test can be done on bone marrow (or via blood test). In short, MRD shows how you are responding to treatment. The goal is MRD-negative — less than 1 myeloma cell per 1 million bone marrow cells. People who test MRD-negative are less likely to relapse.
Research has identified at least a dozen different subtypes of multiple myeloma. Each type has its own set of genetic markers and mutations, which means each type might respond differently to treatments. Genome sequencing can be used to determine what kind of multiple myeloma a person has.
Genome sequencing examines the DNA molecules in cancer cells and searches for mutations. It helps determine how the cells “work” — how they grow, how they hide from the immune system, and how they may react to different treatments. This offers valuable information about prognosis and treatment.
A developing test called gene expression profiling (GEP) looks at RNA instead of DNA. RNA helps regulate cell processes like gene expression, communication between cells, and building needed proteins. Right now, there isn't a standard for GEP, so it isn't widely available.
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