What is the TPHA test?

Question

Hello doctor,

I had unprotected anal sex with a girl a few months ago. I rule out HIV, HBsAg, HCV, and VDRL after 12 weeks of exposure and the results are non-reactive. I also rule out VDRL and TPHA after 105 days of exposure. VDRL-RPR is non-reactive with a titer of one to two. TPHA antibody is non-reactive and the value is 4.8 (normal value 0.2 to 5). I want to know that my TPHA test result value is close to 5. Is my TPHA test alarming? Should I do the TPHA test again?

Kindly suggest.

Answer 1

Hello,

Welcome to icliniq.com.

I read your query and understand your concern.

Your concern is regarding syphilis detection. If you have acquired syphilis (sexually transmitted infection), a small ulcer would be developed at the exposure site. You have no ulcer development.

Diagnosis of syphilis is based on serological tests and antigen detection molecular testing. The serological test is used most commonly for syphilis detection.

Tests detect antibodies either lipoidal material from the damaged cell (called non-treponemal tests like RPR (rapid plasma reagin) and VDRL (venereal disease research laboratory)) or antibodies against specific treponemal components (called treponemal tests like TPHA (Treponema pallidum haemagglutination test), and FTA ABS (fluorescent treponemal antibody absorption).

TPHA is considered a confirmatory test, having a sensitivity of 85 to 100% and a specificity of around 98%. Along with serological tests, clinical correlation was also done.

As there is no ulcer history, and VDRL and TPHA are negative, there is no need for additional testing. If ulcers, enlarged lymph nodes, or fever occur, repeat the TPHA.

I hope this helps.

Take care.