Borrelia burgdorferi IgM Antibody (Serum/Plasma)

What This Test Measures

The test looks for **IgM antibodies**—a type of immune protein your body makes to fight *Borrelia burgdorferi*. These antibodies can appear within weeks of infection but may not be present in all cases, especially if symptoms are mild or treatment started early. The test is often used as part of a screening process, not as a definitive diagnosis alone.

How the Test Works

Blood is drawn and sent to a lab where it’s analyzed using an **immunoassay** method. This detects the presence of IgM antibodies against the Lyme disease bacterium, though results can vary depending on when testing occurs relative to infection timing.

When You Might Need This Test

Your doctor may recommend this test if you’ve had symptoms of Lyme disease (e.g., fever, rash, joint pain) and suspect exposure to ticks in an endemic area (e.g., Northeast, Midwest U.S., or other regions where Lyme is common). It’s sometimes used alongside other tests, like IgG antibodies, for confirmation.

Limitations and Considerations

IgM antibodies may not always be detected early in infection, especially if symptoms are mild. False positives can rarely occur, though this is uncommon. Results should be interpreted by your healthcare provider in the context of your symptoms, travel history, and other test results.