Treponema pallidum Antibodies TPHA (Syphilis) (CSF)

Specimen Required

CSF

Fasting Required

Purpose of the Test

The TPHA test is performed to detect the presence of antibodies against Treponema pallidum, the bacterium that causes syphilis, in cerebrospinal fluid (CSF). The test helps in the diagnosis of neurosyphilis, a serious complication of syphilis that affects the central nervous system.

When this test is required

The TPHA test in CSF is requested when a person is suspected of having neurosyphilis, based on symptoms and/or a positive syphilis test result. The test may also be requested for people who have a high risk of contracting syphilis or have tested positive for syphilis in the past.

What the Test Detects

The TPHA test is a serological test that detects antibodies against Treponema pallidum in cerebrospinal fluid (CSF). The test uses a technique called agglutination, where the patient’s CSF is mixed with a solution containing inactivated T. pallidum antigens. If antibodies are present in the CSF, they will bind to the antigens, causing them to clump together or agglutinate. This reaction is then detected using a microscope or other specialized equipment.

Preparation for the Test

No specific preparation is needed for the TPHA test. However, if the test is being performed along with a lumbar puncture (a procedure to collect CSF), the healthcare provider may ask the patient to fast for a few hours before the procedure.

Sample Requirements

A sample of cerebrospinal fluid (CSF) is required for this test. CSF is a clear, colorless fluid that surrounds the brain and spinal cord.

Additional Notes

The TPHA test is a sensitive and specific test for the diagnosis of neurosyphilis. However, the test may be falsely negative in some cases, especially in people with early or late stages of syphilis, or in people who have been previously treated for syphilis. The test may also be falsely positive in people who have other conditions that can cause antibodies to cross-react with T. pallidum antigens, such as Lyme disease or autoimmune disorders. A positive TPHA test result should always be interpreted in conjunction with other test results and clinical findings.

Selected Tests