Serum FTA-Absorption (Fluorescent Treponemal Antibodies)

Specimen Required

3-5cc Clotted Blood or Serum

Fasting Required

Purpose of the Test

The serum FTA-absorption test is used to diagnose syphilis, an infection caused by the bacterium Treponema pallidum. The test is used to confirm a positive result on a screening test for syphilis, such as the Venereal Disease Research Laboratory (VDRL) or Rapid Plasma Reagin (RPR) test.

When this test is required

The test may be ordered when an individual has a positive result on a screening test for syphilis and the healthcare provider wants to confirm the diagnosis. It may also be ordered if someone has signs and symptoms of syphilis, such as a genital ulcer, rash, or fever.

What the Test Detects

The serum FTA-absorption test measures the level of antibodies in the blood that are produced in response to the bacterium Treponema pallidum, which causes syphilis. The test involves exposing the blood sample to fluorescently labeled T. pallidum antigens and then measuring the amount of fluorescence that is absorbed by the antibodies in the sample.

Preparation for the Test

No special preparation is needed for this test.

Sample Requirements

The test requires a blood sample, which is typically collected via a needle inserted into a vein in the arm.

Additional Notes

The serum FTA-absorption test is a highly specific test for syphilis, which means that it rarely produces false positive results. However, it is possible for the test to produce false negative results in individuals who have early-stage syphilis or who have received treatment for syphilis. It is also possible for the test to produce false negative results in individuals who have HIV infection, as HIV can suppress the immune system and interfere with the production of antibodies to T. pallidum.

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