What it measures
Antibodies to Borrelia burgdorferi, the bacteria that cause Lyme disease, which are spread by tick bites. Labs usually run a screening test first and check a positive with a second test called an immunoblot.
Why people test it
- Measured after a tick bite followed by symptoms such as a spreading rash, fever or aching joints.
- Investigating symptoms that could be Lyme disease when no rash was seen.
Typical range
There is no numeric range. The result is reported as positive, negative or equivocal, and a positive screen is usually checked with an immunoblot. The report shows how that lab reports it.
Finger-prick or vein?
A finger-prick sample is usually fine for an antibody test like this, and some providers offer a home kit. Others take blood from a vein.
The NHS notes that Lyme disease blood tests are not always accurate in the early stages, as antibodies take time to appear.