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Gamma Globulin, SPEP (g/dL)

The amount of protein in the gamma zone on serum electrophoresis, mostly antibodies. Reported in g/dL.

AI-verified against cited sources. Awaiting expert reviewLOINC 2874-6

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What it is

Protein electrophoresis uses an electric current to sort the proteins in your blood serum into groups. The gamma group sits at the end of the tracing and holds most of your antibodies, which are also called immunoglobulins. About 80% of it is IgG, with smaller shares of IgA and IgM. This result gives the amount of protein in that group in g/dL. A separate result gives the same group as a percent of total protein.

Why it matters

The gamma band shows how much antibody protein is in your serum and what its pattern looks like. A broad, even rise often reflects long-running inflammation, infection or liver disease. A narrow spike can mean one group of plasma cells is making a single antibody (a monoclonal protein), so clinicians look at the shape of the tracing as well as the number. A low gamma band can go with low antibody levels. Your clinician reads this together with the rest of the pattern.

If it’s low

A lower gamma band means less antibody protein is present. Many people just under the lower limit have no problem. A clearly low result can go with low antibody levels from a medicine, protein loss or a blood condition. Many other things can cause this, and your clinician can put it in context.

Common causes

  • A result just under the lower limit, which happens in a small share of healthy people because ranges are set that way
  • Medicines that suppress the immune system, such as rituximab, steroids and chemotherapy
  • Protein loss through the kidneys (nephrotic syndrome) or the gut (protein-losing enteropathy)
  • Blood cancers such as chronic lymphocytic leukemia or multiple myeloma, sometimes without any spike
  • A primary antibody deficiency such as common variable immunodeficiency (uncommon)
  • Malnutrition or severe burns

What can help

  • Ask whether quantitative IgG, IgA and IgM would confirm a low antibody level
  • Ask whether a medicine could be lowering it
  • Ask whether urine protein or kidney tests are worth a look

If it’s high

A higher gamma band means more antibody protein is present. Most often it is a broad rise caused by inflammation, infection or liver disease. Less often it comes from one clone of plasma cells making a single antibody. Many other things can cause this, and your clinician can put it in context.

Common causes

  • Long-lasting (chronic) infections, including viral hepatitis, HIV and tuberculosis
  • Autoimmune and connective tissue conditions, such as lupus, rheumatoid arthritis or sarcoidosis
  • Liver conditions, including cirrhosis, autoimmune hepatitis and alcohol-related liver disease
  • Long-running inflammatory conditions, including inflammatory bowel disease and chronic lung conditions
  • Blood and lymph conditions, such as lymphoma or leukemia
  • A monoclonal gammopathy, such as MGUS, multiple myeloma, Waldenström macroglobulinemia or amyloidosis

What can help

  • Ask whether the tracing shows a broad rise or a narrow spike
  • Ask whether immunofixation or quantitative IgG, IgA and IgM would help
  • Ask whether liver tests and inflammation tests fit with this result

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

The usual range depends on age. Choose an age to see the one that applies.

Children and teens 3 ranges

See Gamma Globulin by age and sex, with the U.S. survey numbers where they exist.

What can affect your result

  • Inflammation and infection: a broad rise in the gamma band often follows them
  • Fluid status: being low on fluids concentrates all proteins and can nudge every fraction up
  • Medicines that suppress the immune system lower antibody levels
  • Method: capillary and gel systems give different intervals
  • A blood sample with hemolysis, or fibrinogen when plasma is used, can create a false band
  • A blood sample in which red cells broke open (hemolysis) can distort the tracing and create false patterns.
  • Plasma instead of serum adds fibrinogen, which can show up as an extra band. ARUP does not accept plasma for this test.
  • C-reactive protein sits between the beta and gamma zones, so a high CRP during acute illness can add to the apparent gamma band (AFP 2005).
  • Certain medicines can affect protein results (MedlinePlus). Check with your clinician before changing any medicine.
  • Some sources say you may be asked not to eat or drink for up to 12 hours before the draw (MedlinePlus), while ARUP lists no preparation. Follow the instructions from your lab.

Depends on the cause. A broad rise follows inflammation or infection and can take weeks to settle; a monoclonal protein changes slowly.

When to talk to a clinician

Talk with your clinician if your lab flagged this result, or if the report describes a narrow band or spike in the gamma zone. Let them know sooner about bone pain or back pain that has no clear cause, a fracture after a minor injury, numbness or tingling in your hands or feet, unusual tiredness, or repeated infections.

Questions you could ask

  • How does the gamma result fit with my other protein fractions?
  • Does the graph show a broad rise or a narrow spike?
  • Could an infection, an inflammatory condition or a liver condition explain it?
  • Would quantitative IgG, IgA and IgM or immunofixation add anything?
  • Could one of my medicines or another condition be lowering my antibody level?
  • Should we check IgG, IgA and IgM?

Questions people ask

Does a high gamma band mean I have myeloma?

Usually not. A broad rise is more often caused by infection, inflammation or a liver condition. A narrow spike is what prompts clinicians to look for a monoclonal protein, and further tests such as immunofixation are then used.

What is the difference between the g/dL result and the percent result?

The g/dL result is the amount of protein in the gamma zone. The percent result is the share of your total serum protein that is in that zone. You can turn percent into g/dL by multiplying by your total protein and dividing by 100.

Why does my lab's range differ from the one shown here?

Labs use different instruments and set ranges from different groups of healthy people. For adults, Labcorp prints 0.4–1.8 g/dL, ARUP prints 0.62–1.51 g/dL, and MedlinePlus lists 0.8–1.8 g/dL as an example. Use the range printed on your own report first.

Show the science and sources

Units

  • 1 g/dL = 1 g/dL
  • 1 g/dL = 10 g/L

Open the Gamma Globulin unit converter

Is a change real?

Gamma Globulin naturally varies about 14.6% from test to test in the same healthy person. Between two results from the same lab, a change of roughly 45% or more is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: Desirable Biological Variation Database specifications, 2014 update (Minchinela J, Ricos C, et al.; the 'Ricos database', a compilation of median published CVI/CVG).

For clinicians and researchers

Immunoglobulins migrate mainly in the gamma region, and about 80% of the immunoglobulin in the gamma zone is IgG (Mayo); immunoglobulins can also be found across the rest of the tracing, and C-reactive protein sits between the beta and gamma zones (AFP 2005). A monoclonal protein appears as a sharp, well-defined band with a single heavy chain and a light chain, while a polyclonal rise is a broad, diffuse band (AFP 2005). A narrow spike can also appear in the beta or alpha-2 zones. Serum protein electrophoresis shows a spike in only about 82% of people with myeloma in one series, and about 10% of myeloma patients without a spike have hypogammaglobulinemia (AFP 2005), and ARUP notes immunofixation is more sensitive for small M-proteins. Quantitative IgG, IgA and IgM, not electrophoresis, are the direct way to measure each antibody class, and when a monoclonal protein sits on a polyclonal background, serum protein electrophoresis should be used to follow the monoclonal protein (Mayo). Labcorp prints 0.4–1.8 g/dL for adults (0.6–1.5 for ages 6 to 17), ARUP reports gamma by quantitative capillary electrophoresis at 0.62–1.51 g/dL alongside a monoclonal protein result (<=0.00 g/dL), ABIM lists 0.7–1.7 g/dL and MedlinePlus gives 0.8–1.8 g/dL as an example. g/dL = percent x total protein / 100, so the g/dL and percent results are separate markers. Intervals are method specific.

LOINC 2874-6 (primary). Specimen: serum.

Sources

  1. Protein Electrophoresis, Serum (test 0050640), ARUP Laboratories
  2. Pediatric Testing Reference Ranges (includes adult intervals for Labcorp tests 001487, 001776, 001784, 001792 and 001834), Labcorp Diagnostics
  3. Protein electrophoresis - serum, MedlinePlus (National Library of Medicine) (2026)
  4. ABIM Laboratory Test Reference Ranges, January 2026, American Board of Internal Medicine (2026)
  5. Understanding and Interpreting Serum Protein Electrophoresis, American Family Physician (2005)
  6. Immunoglobulin G (IgG), Serum (test ID IGG), Mayo Clinic Laboratories
  7. Immunoglobulin Replacement Therapy in Secondary Hypogammaglobulinemia, Frontiers in Immunology (2014)
  8. LOINC code lookup (NLM Clinical Tables), National Library of Medicine

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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