Serum/plasma concentration of immunoglobulin G (IgG) antibodies against *Borrelia burgdorferi* (Lyme disease spirochete)

What This Test Measures

IgG antibodies are part of your immune system’s long-term defense. When you’re infected with *Borrelia burgdorferi*, your body produces these antibodies to remember the infection. This test detects these antibodies in your blood, which can indicate past or lingering exposure to the bacterium.

Why It Matters in Diagnosis

While IgG antibodies are useful for diagnosing Lyme disease in early or late-stage infections, they may not be detected immediately after infection. Early-stage tests often rely on different antibodies (like IgM) or other markers. This test is particularly useful for confirming Lyme disease in cases where symptoms have been present for months or years.

When You Might Need This Test

Your healthcare provider may recommend this test if you have symptoms of Lyme disease (such as a bull’s-eye rash, joint pain, or neurological issues) and recent exposure to ticks, especially in endemic regions. It may also be used to monitor treatment progress or assess past exposure in individuals with chronic symptoms.

What to Expect Before the Test

No special preparation is needed for this test. You’ll have a small needle inserted into your arm to draw blood. The process usually takes a few minutes. If you’re pregnant, have a bleeding disorder, or take blood-thinning medications, let your provider know before the test.