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Lab test

FTA-ABS Test

The FTA-ABS test measures antibodies against Treponema pallidum, the organism associated with syphilis, in a serum sample. Quest lists it as a confirmation-type test, and it does not distinguish syphilis from related treponemal diseases such as yaws, pinta and bejel.

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About this test

FTA-ABS uses an immunofluorescent assay to detect antibodies reactive against Treponema pallidum in serum. Quest describes these antibodies as becoming reactive four to six weeks after infection and typically remaining reactive for many years afterward.

People who come to this test are usually following up on a reactive screening result and need a more specific antibody test related to exposure to Treponema pallidum. Because the antibodies it detects don't distinguish syphilis from related treponemal diseases such as yaws, pinta and bejel, and because reactivity can persist for years, the result is read by the ordering clinician alongside history and any earlier test results.

Test details

CollectionQuest patient service center

Quest resources

Additional details

What this test looks at

The test reports a single antibody result. Quest lists this same test under several names, including Fluorescent Treponemal Antigen, Treponemal Antibody Fluorescent (FTA) and Syphilis Confirmation Test, all referring to this immunofluorescent antibody assay.

This test isn't part of the Celio Health store at the moment, so it can't be ordered or requested here. The test menu lists everything that can.

Laboratory results should always be interpreted by a licensed clinician who knows your health history. This page is information about a test, not medical advice.

Frequently asked questions

What does the FTA-ABS test measure?

It measures antibodies against Treponema pallidum in serum, using an immunofluorescent assay.

How is the sample collected?

The test uses a serum sample from a routine blood draw.

Do I need to prepare for this test?

No preparation instructions are listed for this test, though people follow any instructions their ordering clinician provides.

Can this test monitor how treatment is working?

No. Quest notes that reactivity does not change with treatment response, so FTA-ABS is not suitable for monitoring therapy.

Does a reactive result mean it is definitely syphilis?

Not on its own. Quest notes this assay does not distinguish syphilis from other treponemal diseases such as yaws, pinta and bejel, so the ordering clinician reads it alongside history and other findings.

Last updated 2026-09-18 · How we write about lab testing

Educational content

This page is for general educational purposes only. It is not medical advice, and it is not a substitute for consultation with a qualified healthcare professional. Laboratory results should always be interpreted by a licensed clinician who knows your health history. If you have questions about your health or your results, talk with your doctor. If you think you may be experiencing a medical emergency, call 911.