Immunoglobulin M (IgM) in Serum

What Does IgM Measure?

IgM is one of the primary antibodies your immune system produces early in an infection. It helps your body identify and neutralize harmful substances, such as bacteria or viruses. IgM levels can rise shortly after exposure and remain elevated for a longer period compared to other antibodies like IgG.

Why Might Your Doctor Order This Test?

Your doctor may order an IgM serum test to diagnose or monitor conditions such as infections (e.g., hepatitis, certain bacterial infections), autoimmune diseases, or to assess immune responses in chronic conditions. It can also help track the progression or treatment response in some medical conditions.

Sample Preparation and Testing Process

For this test, a blood sample is collected from a vein in your arm. The blood is then processed to separate the serum, which is sent to a lab for analysis. The IgM level is measured using an immunoassay method, which detects the presence and amount of IgM antibodies in your serum.

What Are Possible Results?

Results are typically reported as a numerical value representing the concentration of IgM in your serum. While reference ranges can vary by lab, elevated IgM levels may suggest an active infection, immune response, or certain medical conditions. Lower than expected levels might indicate immune system dysfunction or specific genetic conditions.