Introduction of TPHA and VDRL Tests
Table of Contents
Doctors use the TPHA (Treponema pallidum Hemagglutination Assay) test to detect antibodies against Treponema pallidum. Since syphilis remains a significant global health concern, early diagnosis is crucial. This test identifies treponemal antibodies in serum or plasma. Because it detects both past and present infections, it serves as a confirmatory test. TPHA relies on hemagglutination to detect antibodies. Moreover, it remains highly specific for Treponema pallidum infections. Because it confirms syphilis, doctors use it after a reactive non-treponemal test like VDRL. Furthermore, it helps assess disease progression. Unlike VDRL, TPHA stays positive for life. For this reason, past and active infections cannot be distinguished. Hospitals and laboratories use TPHA as a routine syphilis diagnostic tool. Thus, it plays a key role in syphilis detection.
The VDRL (Venereal Disease Research Laboratory) tests screen for syphilis by detecting reagin antibodies. Since it is a non-treponemal test, it does not directly detect Treponema pallidum. This test uses cardiolipin antigen to detect antibodies. Because reagin antibodies rise during active infection, VDRL helps in early diagnosis. Doctors prefer VDRL for initial screening. However, it may show false-positive results in autoimmune diseases, pregnancy, or infections. VDRL titers indicate disease activity. Thus, physicians use it to monitor treatment response in syphilis patients. Unlike TPHA, VDRL titers decrease after successful treatment. For this reason, it helps determine cure or reinfection. Hospitals use VDRL in blood and CSF samples to detect neurosyphilis. Overall, it remains an essential test for syphilis diagnosis and management.
Test Result, Unit, Normal Range, and Test Method

Clinical Significance
1. TPHA (Treponema pallidum Hemagglutination Assay) Test
- Doctors use the TPHA test to confirm syphilis infection. Since it detects treponemal antibodies, it provides high specificity.
- This test remains positive for life. Therefore, it cannot differentiate between past and current infections.
- Because it confirms syphilis, doctors use it after a reactive VDRL or RPR test. Moreover, it aids in staging syphilis.
- Hospitals include TPHA in syphilis screening programs. For this reason, it helps detect asymptomatic cases.
- Patients with secondary and latent syphilis often test positive. Furthermore, it helps track disease progression in untreated individuals.
- Doctors rely on TPHA for prenatal syphilis screening. Because congenital syphilis causes severe complications, early detection remains essential.
- Researchers study TPHA-positive cases to understand syphilis epidemiology. Thus, it plays a role in public health surveillance.
2. VDRL (Venereal Disease Research Laboratory) Test
- The VDRL test serves as an initial syphilis screening tool. Since it detects reagin antibodies, it helps identify active infections.
- Doctors use VDRL titers to monitor disease progression. Because titers correlate with infection severity, they guide treatment decisions.
- Unlike TPHA, VDRL titers decline after successful treatment. For this reason, doctors use it to confirm treatment responses.
- False-positive VDRL results occur in autoimmune diseases, pregnancy, and other infections. Therefore, confirmatory testing with TPHA remains necessary.
- Neurosyphilis diagnosis requires VDRL testing in cerebrospinal fluid (CSF). Furthermore, CSF-VDRL has a higher specificity for neurosyphilis detection.
- Clinicians monitor reinfection risk using VDRL. Because declining titers indicate successful treatment, rising titers suggest possible reinfection.
- Public health programs rely on VDRL for syphilis control efforts. Thus, mass screening initiatives help reduce disease transmission.
Keynotes on TPHA and VDRL Tests
Keynotes of TPHA and VDRL Tests
1. TPHA (Treponema pallidum Hemagglutination Assay) Test
- TPHA detects antibodies against Treponema pallidum. Since it is a treponemal test, it confirms syphilis infection.
- This test remains positive for life. Therefore, it cannot distinguish between past and current infections.
- Doctors perform TPHA after a reactive VDRL test. Because it provides higher specificity, it serves as a confirmatory test.
- Hospitals use TPHA in prenatal syphilis screening. Since congenital syphilis causes severe complications, early detection is crucial.
- TPHA shows high sensitivity in secondary and latent syphilis. Moreover, it helps in staging the disease.
- Patients with HIV may show variable TPHA results. For this reason, additional testing remains necessary for accurate diagnosis.
- Public health programs include TPHA in syphilis control efforts. Thus, mass screening helps detect hidden infections.
2. VDRL (Venereal Disease Research Laboratory) Test
- VDRL detects reagin antibodies in syphilis. Since it is a non-treponemal test, it helps in initial screening.
- Unlike TPHA, VDRL titers decline after successful treatment. Therefore, it helps monitor treatment response.
- Doctors perform VDRL on cerebrospinal fluid (CSF) to diagnose neurosyphilis. Because CSF-VDRL has high specificity, it confirms central nervous system involvement.
- False-positive VDRL results occur in pregnancy, autoimmune diseases, and viral infections. For this reason, confirmatory testing with TPHA remains necessary.
- Clinicians use VDRL titers to track disease progression. Furthermore, rising titers may indicate reinfection or treatment failure.
- Hospitals rely on VDRL for syphilis screening programs. Since early detection prevents complications, routine testing remains essential.
- Mass screening campaigns include VDRL testing. Thus, it plays a key role in reducing syphilis transmission.
Further Readings
- https://www.carehospitals.com/diagnostics/vdrl-test
- https://www.sprintdiagnostics.in/hyderabad/test/vdrl-reflex-tpha-confirmation
- https://www.leangene-jo.com/images/LEANGENE/PDFs/MICROBIOLOGY/rpr_vdrl_2013011.pdf
- https://drwalias.com/vdrl-tpha-positivity/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC2652238/
- https://www.jpatholtm.org/journal/view.php?number=16035
- https://sti.bmj.com/content/54/3/151
- https://www.mountsinai.org/health-library/tests/vdrl-test
- https://www.ijord.com/index.php/ijord/article/view/222
- https://www.semanticscholar.org/paper/USE-OF-TPHA-AND-VDRL-IN-THE-DIAGNOSIS-OF-SYPHILIS-Kulshrestha-Kulshrestha/8f4390b57d6c00e8b0f665609263e1caa872b7ec
- https://redcliffelabs.com/treponema-pallidium-hemagglutination-assay-tpha
- https://www.ijcmas.com/vol-3-5/Shweta%20Sharma,%20et%20al.pdf