Description

The Lyme disease IgG and IgM blood test measures the levels of antibodies in your blood that fight the bacteria that causes Lyme disease. The test is used to help diagnose Lyme disease, a bacterial infection spread by infected tick bites. 

What the test measures 

IgM

  • The first antibody secreted by B cells in response to a foreign antigen. A positive IgM result may indicate a current or recent infection.

IgG

  • An antibody produced after the body has been exposed to an antigen for a while. IgG antibodies can remain in the blood even after the infection has ended.

When the test is used

  • A doctor may order this test if you have symptoms of Lyme disease and have been exposed to infected ticks. 
  • The test can help confirm a positive result from an initial test. 
  • The test can help determine if you have a current or past infection. 

What the results mean

  • A positive IgM result may indicate a current or recent infection. 
  • A positive IgG result may indicate a current or past infection. 
  • A positive IgG and negative IgM result may indicate a past infection or an infection that's been present for more than four weeks. 

Fasting not required.