IgM
IgM (immunoglobulin M) is the first antibody produced by the immune system in response to a new infection. It is the largest antibody and is found mainly in the blood.
Category: Inflammation & Immune
Also known as: igm, immunoglobulin m, serum igm, Immune globulin M
Reference range: 40–230 mg/dL (Source: ABIM)
Standard unit: mg/dL
High values may indicate
High IgM levels may indicate an acute or recent infection, Waldenstrom's macroglobulinemia (lymphoplasmacytic lymphoma), primary biliary cholangitis, or hyper-IgM syndrome.
Low values may indicate
Low IgM levels may indicate immunodeficiency disorders, multiple myeloma (non-IgM type), or conditions causing protein loss, and may increase susceptibility to infections.
Frequently asked questions
- What is a normal IgM level?
- A typical reference range for IgM is 40–230 mg/dL (source: ABIM). Reference ranges vary by laboratory, age, and sex, so always compare against the range on your own lab report.
- What units is IgM measured in?
- IgM is most commonly reported in mg/dL. Labs in different countries may use other units — you can convert between them with BloodId's blood test unit converter.
- Where do IgM reference ranges come from?
- BloodId uses ABIM standard reference ranges and educational information from MedlinePlus (see our methodology). Reference ranges still vary by lab, age, and sex, so always compare against your own report.
- Can I track IgM over time?
- Yes. Upload results from any lab and BloodId charts your IgM over time against its reference range, so you can see whether the trend is rising, falling, or stable.