Protein electrophoresis is primarily used to diagnose blood cancers like multiple myeloma and Waldenström macroglobulinemia, but it also helps identify liver disease, kidney disease, chronic infections, and autoimmune conditions. The test separates blood proteins into five distinct groups based on their electrical charge, creating a pattern that shifts in characteristic ways depending on what’s going wrong in the body.
How the Test Works
A small sample of your blood serum is placed on a special surface and exposed to an electric current. Different proteins move at different speeds based on their size and charge, spreading out into five visible bands: albumin, alpha-1 globulins, alpha-2 globulins, beta globulins, and gamma globulins. Each band represents a family of proteins with specific jobs in the body, from fighting infections to transporting nutrients. When one band is too high, too low, or shows an unusual spike, it points toward specific diseases.
Normal reference ranges give doctors a baseline for comparison. Albumin, the largest band, typically falls between 3.75 and 5.01 g/dL. The gamma globulin fraction, which contains your immune system’s antibodies, normally ranges from 0.62 to 1.51 g/dL. Deviations from these ranges in specific combinations create recognizable patterns tied to particular conditions.
Multiple Myeloma and Related Blood Cancers
The most well-known use of protein electrophoresis is screening for multiple myeloma, a cancer of plasma cells in the bone marrow. In myeloma, one clone of plasma cells multiplies out of control and produces massive amounts of a single identical antibody. This shows up on the electrophoresis readout as a sharp, narrow spike called an M-spike or M-protein, usually in the gamma region. That spike looks dramatically different from the normal broad, gentle curve of healthy antibody production.
Diagnosing myeloma requires three things to be present together: evidence of abnormal plasma cells in the bone marrow, an M-spike on serum or urine protein electrophoresis, and signs of organ damage such as high calcium, kidney problems, anemia, or bone lesions. About 3% of myeloma cases are “non-secretory,” meaning the cancer cells don’t release detectable protein into the blood, so electrophoresis alone can miss them.
The size of the M-spike also helps distinguish between different stages of disease. A precancerous condition called MGUS (monoclonal gammopathy of undetermined significance) produces a smaller spike and involves fewer abnormal cells, with no organ damage. Smoldering myeloma sits between MGUS and active myeloma, defined by an M-protein of 3 g/dL or higher or at least 10% abnormal plasma cells in the bone marrow, but still without symptoms or organ damage. The Mayo Clinic’s “20/20/2” risk model uses a serum monoclonal protein level above 2 g/dL as one of its key risk factors for progression.
Waldenström macroglobulinemia, a rarer blood cancer, also produces a distinctive M-spike. The difference is that the abnormal protein is specifically an IgM antibody, which is much larger than the IgG antibodies typical of myeloma. Diagnosis requires the presence of a monoclonal IgM protein plus at least 10% abnormal cells in the bone marrow. One reported case showed an IgM level of 3,470 mg/dL with an M-spike of 2.1 g/dL. Patients with an IgM monoclonal protein below 3 g/dL and fewer than 10% abnormal cells are classified as having IgM MGUS rather than active Waldenström disease.
Liver Disease
Liver problems produce some of the most recognizable pattern changes on protein electrophoresis because the liver manufactures most of the proteins being measured. Cirrhosis causes a broad, elevated gamma globulin band rather than the sharp spike seen in cancer. This broad increase, called a polyclonal gammopathy, reflects the immune system’s widespread overactivation rather than a single clone of cells misbehaving. In advanced cirrhosis, the beta and gamma bands can merge together into a continuous bridge pattern.
Severe liver disease also lowers albumin levels, since the damaged liver can’t produce enough. The alpha-1 band may drop as well, because the liver is the primary source of alpha-1 antitrypsin, one of the main proteins in that fraction. Biliary cirrhosis, which involves the bile ducts rather than the liver tissue itself, tends to increase the beta globulin fraction specifically. Different forms of liver disease, including alcohol-related damage, autoimmune hepatitis, viral hepatitis, and primary sclerosing cholangitis, all produce polyclonal gammopathy patterns, though the exact shape varies.
Kidney Disease
Nephrotic syndrome, a condition where damaged kidneys leak large amounts of protein into the urine, creates a distinctive two-part pattern: albumin drops significantly while alpha-2 globulins rise. The albumin drops because it’s small enough to escape through the damaged kidney filters. The alpha-2 fraction rises because it contains alpha-2 macroglobulin, a protein too large to pass through even damaged kidneys, so the body ramps up its production to compensate for all the other proteins being lost.
Multiple myeloma itself frequently causes kidney damage, so protein electrophoresis sometimes reveals both an M-spike and signs of kidney impairment in the same patient. Urine protein electrophoresis can be ordered alongside the blood test to check for Bence Jones proteins, which are fragments of abnormal antibodies that pass through the kidneys and can directly damage them.
Inflammation and Autoimmune Conditions
Acute inflammation from infections, injuries, or surgery causes the alpha-1 and alpha-2 bands to rise. These fractions contain “acute phase reactants,” proteins the body churns out as part of its inflammatory response. The alpha-2 band increases because it includes haptoglobin and ceruloplasmin, both of which spike during active inflammation.
Chronic inflammatory and autoimmune conditions like lupus and rheumatoid arthritis tend to elevate the gamma globulin region in a broad, diffuse pattern. This polyclonal gammopathy looks similar to the pattern seen in liver disease and reflects the immune system producing excess antibodies of many different types. Granulomatous diseases, Hodgkin’s disease, and chronic lymphocytic leukemia also produce elevated gamma globulins, which is why the pattern raises a flag but doesn’t pinpoint a single diagnosis on its own.
Alpha-1 Antitrypsin Deficiency
A noticeably decreased alpha-1 band can signal alpha-1 antitrypsin deficiency, a genetic condition that increases the risk of lung disease and liver damage. This protein normally protects lung tissue from enzyme damage, so people who produce too little of it are vulnerable to early-onset emphysema. Because the alpha-1 fraction is small to begin with, even moderate reductions are visible on the electrophoresis tracing and prompt further genetic testing.
What Happens After an Abnormal Result
Protein electrophoresis is a screening tool, not usually a final answer. When the test shows an abnormal pattern, a follow-up test called immunofixation electrophoresis is typically the next step. Immunofixation identifies exactly which type of antibody is causing an M-spike (IgG, IgA, IgM, or light chains only), which matters because different antibody types point to different cancers and carry different prognoses. An IgA variant of myeloma, for example, sometimes produces an M-spike that migrates to the beta region instead of the gamma region, making it easy to miss without immunofixation.
Immunofixation is especially important when the gamma region looks unusually low. Hypogammaglobulinemia, a flat or diminished gamma band, might seem like the opposite of cancer. But some myeloma patients show suppressed normal antibodies without a visible spike, because the cancer cells produce proteins at levels too low to form an obvious peak while still crowding out healthy immune function. Immunofixation can reveal small monoclonal proteins hiding within an otherwise unremarkable pattern.
Urine protein electrophoresis is often ordered alongside the blood test when myeloma or a related condition is suspected. Some abnormal proteins, particularly the light chain fragments called Bence Jones proteins, are cleared so quickly from the bloodstream that they show up more reliably in urine. Combining serum and urine electrophoresis with immunofixation and free light chain testing captures nearly all cases of plasma cell disorders, including the small percentage that any single test would miss.