Research Blog

July 7, 2023

Immunoglobulins: IgM

Optimal Takeaways

Immunoglobulin M (IgM) plays a crucial role in the early immune response to infection and is protective against inflammation, atherosclerosis, and autoimmunity. Low IgM levels can occur due to various factors, such as hypoproteinemia, AIDS, immunosuppression, and medication use. High IgM levels can be seen in acute and chronic infections, autoimmune diseases, and chronic liver disorders. IgM is essential in combating various bacterial, fungal, viral, and parasitic infections, and it helps clear apoptotic cells.

Standard Range: 50-300 mg/dL mg/dL (0.5 – 3.00 g/L)

The ODX Range: 56 - 230 mg/dL (0.56 - 2.3 g/L)

Low IgM can occur with hypoproteinemia, agammaglobulinemia, AIDS, immunosuppression, leukemia, and IgG or IgA multiple myeloma (Pagana 2021). Levels may decrease with gastrointestinal losses, malignancy in general, and medication use, including phenytoin, glucocorticoids, penicillamine, and sulfasalazine (Agarwal 2007).

High IgM levels can occur with acute and chronic infection, autoimmune disease, chronic liver disorders, and macroglobulinemia (Pagana 2021). Higher IgM may be seen in primary biliary cirrhosis, hypertriglyceridemia, or low HDL. IgM serum levels may be up to 30% higher in females, possibly due to hormonal effects (Gonzalez-Quintela 2008). Elevated IgM is also seen in hyper-IgM syndromes where IgM may be elevated or normal while IgA and IgG are decreased (Agarwal 2007).


The IgM immunoglobulin is involved in the immune response to infection and determining ABO blood types and rheumatoid factor. Evaluating measles exposure incorporates IgG and IgM testing. Increased IgG indicates past infection or immunization, while a four-fold increase in IgM reflects a current infection (Pagana 2021). IgM is produced early in response to pathogens or antigens and activates the classical complement system (Justiz 2021). It is considered a potent agglutinin (Justiz Vaillant 2021). Intake of alcohol, smoking, and aging do not appear to affect IgM levels (Gonzalez-Quintela 2008).

IgM protects against various bacterial, fungal, viral, and parasitic infections and is found in all vertebrate species. It also assists in clearing apoptotic cells and appears to protect against autoimmunity, inflammation, and atherosclerosis (Ehrenstein 2010).

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Agarwal, Shradha, and Charlotte Cunningham-Rundles. “Assessment and clinical interpretation of reduced IgG values.” Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology vol. 99,3 (2007): 281-3. doi:10.1016/S1081-1206(10)60665-5

Dunkelberger, Jason R., and Wen-Chao Song. "Complement and its role in innate and adaptive immune responses." Cell research 20.1 (2010): 34-50.

Ehrenstein, Michael R, and Clare A Notley. “The importance of natural IgM: scavenger, protector and regulator.” Nature reviews. Immunology vol. 10,11 (2010): 778-86. doi:10.1038/nri2849

Gonzalez-Quintela, A et al. “Serum levels of immunoglobulins (IgG, IgA, IgM) in a general adult population and their relationship with alcohol consumption, smoking and common metabolic abnormalities.” Clinical and experimental immunology vol. 151,1 (2008): 42-50. doi:10.1111/j.1365-2249.2007.03545.x

Justiz Vaillant, Angel A., et al. “Immunoglobulin.” StatPearls, StatPearls Publishing, 12 October 2021.

Pagana, Kathleen Deska, et al. Mosby's Diagnostic and Laboratory Test Reference. 15th ed., Mosby, 2021.

Tag(s): Biomarkers

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