Multiple myeloma is a cancer originating in plasma cells, a type of white blood cell found in bone marrow. These abnormal cells multiply uncontrollably, potentially damaging bones, kidneys, and other body parts. Blood tests are important for detecting, diagnosing, and managing multiple myeloma, providing insight into the disease’s presence and activity. They offer information that guides healthcare professionals in developing treatment strategies.
Initial Blood Indicators
A complete blood count (CBC) is often an initial indicator of multiple myeloma. This test measures blood components, and abnormalities can include a low red blood cell count, known as anemia. Anemia is common in multiple myeloma patients, causing fatigue and shortness of breath as cancerous plasma cells crowd out healthy red blood cell production in the bone marrow.
The CBC may also reveal low white blood cell counts (leukopenia) or low platelet counts (thrombocytopenia). Myeloma cells can interfere with the bone marrow’s ability to produce these blood components, increasing infection risk with low white blood cells and bleeding with low platelets. Abnormalities in a blood chemistry panel can raise suspicion. Elevated calcium levels (hypercalcemia) occur because the disease causes bones to break down, releasing calcium into the bloodstream.
Impaired kidney function, indicated by high levels of creatinine and blood urea nitrogen (BUN), is also common. Abnormal plasma cells produce proteins that can block the kidneys’ filtering process, leading to damage. Blood chemistry may also show abnormal total protein levels, and altered albumin and globulin levels, indicating protein imbalances.
Identifying Myeloma-Specific Proteins
Once general indicators suggest an issue, specialized blood tests identify proteins directly linked to multiple myeloma. Serum protein electrophoresis (SPEP) separates blood proteins by electrical charge, detecting an “M-spike” or monoclonal protein. This M-spike is a distinct band of abnormal antibodies produced by cancerous plasma cells and is a hallmark of the disease.
Following SPEP, immunofixation electrophoresis (IFE) is performed to confirm the specific type of M-protein. IFE identifies which class of immunoglobulin (IgG, IgA, or IgM) and which light chain component (kappa or lambda) is overproduced by myeloma cells. This detailed identification is important for accurate diagnosis and disease monitoring.
Quantitative immunoglobulin tests measure the amounts of different antibody types in the blood. In multiple myeloma, these tests show elevated M-protein levels and suppressed normal immunoglobulins, which can compromise the immune system. The serum free light chain (SFLC) assay measures unbound kappa and lambda light chains, often excessively produced by myeloma cells. The ratio between kappa and lambda free light chains is important, as an abnormal ratio indicates a plasma cell disorder.
Assessing Disease Activity and Prognosis
Beta-2 microglobulin (B2M) is a protein whose blood levels can indicate tumor burden, or the amount of cancer cells. Higher B2M levels correlate with more advanced disease and are incorporated into multiple myeloma staging systems.
Lactate dehydrogenase (LDH) is an enzyme found in various body tissues; elevated blood levels suggest more aggressive disease activity. A high LDH level is associated with a less favorable prognosis in multiple myeloma patients. These prognostic markers, along with initial diagnostic tests, provide a clear picture of the disease’s severity and help guide treatment decisions. They are important for ongoing monitoring to assess treatment effectiveness and detect disease progression.