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

What This Test Measures

The test detects IgG antibodies specific to *Borrelia burgdorferi*, a bacterium transmitted by tick bites. These antibodies develop after your immune system has encountered the bacterium, often weeks to months after exposure. The presence of these antibodies suggests past infection, though they may persist long-term.

How the Test Works

Your blood sample is analyzed using an immunoassay (a lab method that detects antibodies). The test identifies IgG antibodies against *Borrelia burgdorferi* proteins, helping differentiate between exposure and active infection.

When You Might Need This Test

Doctors may order this test if you’ve had a tick bite, have symptoms like fever, fatigue, or joint pain, or if you live in an area with high Lyme disease risk. It’s also used to monitor treatment progress or evaluate past exposure in certain clinical scenarios.

What to Expect Before the Test

No special preparation is needed. You’ll have a simple blood draw, usually at a clinic or lab. Wear comfortable clothing and arrive with an empty stomach if instructed, though this is not always required for this test.