Diagnosis and monitoring
Focus on M-protein Testing
M-Protein is an important tumor marker used in the diagnosis, prognosis and monitoring of response to therapy. This individualized tumor marker can be used to follow a patient’s level of malignant cells and measure relative tumor burden.
When Multiple Myeloma is suspected clinically, patients should be tested for the presence of M-proteins using a combination of tests that should include a serum protein electrophoresis (SPEP), serum immunofixation (IFE), and the serum FLC assay.
Serum Protein Electrophoresis
Serum protein electrophoresis (SPEP, SPE) is a blood test that detects and measures M-Protein (30-50 mg/dL).
Urine protein electrophoresis (UPE) detects and measures M-Protein if passing through the kidney and into the urine.
SPE is used for screening, MGUS/SMM monitoring and MM therapy monitoring before CR is reached.
SPE uses measurable conc. ( >1 g/dL) for screening. If not measurable, per guidelines, sFLC should be used.
Immunofixation
Serum immunofixation (IFE, IF) is a blood test that detects and characterizes the isotype (IgM, IgD, IgG, IgA, IgE, and Kappa vs. Lambda) of M-Protein (12-25 mg/dL).
Urine immunofixation (UIFE) detects and characterizes free light chains (aka Bence Jones protein) and IgM, IgD, IgG, IgA, IgE, in the urine.
Hydrashift
Sebia Hydrashift removes interfering immunotherapies, like daratumumab and isatuximab, from immunofixation results. This is useful to help accurately interpret immunofixation results when a patient is receiving these therapies since the treatment itself mimics a M-protein.
Free Light Chain
Serum Free Light Chain ratio (sFLC) is a blood test that measures the ratio of free kappa to free lambda light chains of antibodies. An abnormal ratio indicates, but does not confirm, a plasma cell disorder.
