Treponema Pallidum Haemagglutination(TPHA)

Bacterial/ Viral

Report in 48Hrs

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No Fasting Required

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Used to detect antibodies against Treponema pallidum, the bacterium that causes syphilis

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Treponema Pallidum Haemagglutination (TPHA) Test Information Guide

Why is it done?
- Test Purpose: The TPHA test is a serological assay designed to detect antibodies against Treponema pallidum, the bacterium responsible for syphilis. It measures the presence of specific IgG and IgM antibodies that indicate past or current infection.
- Primary Indications: Diagnosis of syphilis in symptomatic patients with clinical signs such as ulcers (chancre), rash, or systemic symptoms; screening of pregnant women; blood and organ donor screening; contact tracing of exposed individuals; monitoring of treated syphilis; evaluation of suspected congenital syphilis in newborns
- Timing and Circumstances: Performed during routine health screenings, prenatal evaluations, sexually transmitted infection (STI) testing, blood donation screening, and when clinical signs of syphilis are present. Testing is typically done 3-4 weeks after primary infection becomes detectable.
Normal Range
- Reference Values: Negative (Non-reactive): No detectable antibodies to Treponema pallidum; Positive (Reactive): Detectable antibodies indicating infection with T. pallidum.
- Result Interpretation: Results are reported as qualitative: Negative/Non-reactive (no antibodies detected, indicates absence of syphilis infection) or Positive/Reactive (antibodies present, indicates current or past T. pallidum infection). Some laboratories report semi-quantitative titers.
- Units of Measurement: Qualitative determination (Positive/Negative or Reactive/Non-reactive); when quantitative, reported as titer ratio (1:8, 1:16, 1:32, etc.) or IU/mL.
- What Normal vs Abnormal Means: Normal (Negative) = No evidence of syphilis infection; Abnormal (Positive) = Indicates T. pallidum infection, either current active disease or past infection, requiring further investigation and clinical correlation.
Interpretation
- Positive Result Interpretation: Indicates T. pallidum infection. A positive TPHA can reflect: (1) Current active syphilis requiring treatment; (2) Past syphilis that has been treated (antibodies persist for life); (3) Early primary syphilis (positive after 2-4 weeks); (4) Secondary syphilis (highly specific and sensitive); (5) Tertiary syphilis; (6) Latent syphilis (positive without active signs). TPHA remains positive even after successful treatment.
- Negative Result Interpretation: Indicates absence of T. pallidum infection. In the context of clinical symptoms suspicious for syphilis, a negative result may represent: (1) Very early infection (window period before antibodies develop); (2) Unrelated cause of symptoms; (3) Adequate immune response has not yet developed.
- Factors Affecting Results: Timing of infection (early infections may be negative); Prior treatment (doesn't eliminate antibodies); Immunosuppression or HIV coinfection (may delay antibody formation); Certain autoimmune diseases causing false positives; Biological false positives from other conditions (tuberculosis, leprosy, pregnancy); Congenital infection status in newborns.
- Clinical Significance: TPHA is a highly specific and sensitive treponemal-specific test with specificity >98%. It is superior to RPR/VDRL (non-specific tests) for confirming syphilis diagnosis. A positive TPHA should always be confirmed with clinical findings and typically combined with quantitative RPR/VDRL testing to assess disease activity and monitor treatment response.
Associated Organs
- Primary Organ Systems Involved: Reproductive system (primary infection site); Skin and mucous membranes (lesions); Nervous system (neurosyphilis); Cardiovascular system (cardiovascular syphilis); Immune system (systemic involvement).
- Associated Medical Conditions: Primary syphilis (chancre formation); Secondary syphilis (rash, systemic symptoms, lymphadenopathy); Latent syphilis (asymptomatic but infectious); Tertiary syphilis (gummatous lesions); Neurosyphilis (meningitis, general paresis of the insane, tabes dorsalis); Cardiovascular syphilis (aortitis, aortic regurgitation); Congenital syphilis in offspring.
- Diseases Diagnosed or Monitored: Syphilis (all stages); Congenital syphilis; Yaws and pinta (caused by related treponemes); Treponematosis; Investigation of sexually transmitted infections.
- Potential Complications from Abnormal Results: If untreated: progressive neurological damage, blindness, deafness, cardiac complications, aortitis with rupture, dementia, infertility, spontaneous abortion, congenital abnormalities in offspring, transmission to sexual partners.
Follow-up Tests
- Confirmatory and Complementary Tests: RPR (Rapid Plasma Reagin) or VDRL (Venereal Disease Research Laboratory) test - quantitative non-specific test to assess disease activity and monitor treatment; FTA-ABS (Fluorescent Treponemal Antibody Absorption) - additional confirmation test; TP-PA (Treponema Pallidum Particle Agglutination) - alternative confirmatory test; Darkfield microscopy - if primary chancre present.
- Further Investigations for Abnormal Results: Cerebrospinal fluid (CSF) examination if neurosyphilis suspected; Serological tests for HIV and other STIs; Cardiac imaging (echocardiography) for cardiovascular involvement; Ophthalmologic examination for ocular syphilis; Audiologic testing for eighth nerve involvement.
- Monitoring Frequency: For treated early syphilis: RPR/VDRL at 3, 6, and 12 months post-treatment; For late syphilis: RPR/VDRL at 6 and 12 months; For neurosyphilis: CSF repeat testing at 6 months; TPHA remains positive indefinitely after treatment; During pregnancy: initial screening, then annually or as per protocol.
- Related Complementary Tests: IgM-TPHA or IgM FTA-ABS to detect recent/acute infection; IgG testing to confirm past or chronic infection; HIV testing (often coinfected); Herpes simplex serology; Hepatitis B and C screening; Partner notification testing.
Fasting Required?
- Fasting Requirement: NO - Fasting is not required for the TPHA test. This is a serological blood test that can be performed at any time of day regardless of food or fluid intake.
- Patient Preparation Instructions: No special fasting or dietary restrictions; Patients may eat and drink normally; No need to adjust fluid intake; Patient may take routine medications as prescribed; If drawing blood with other tests that may require fasting, follow specific instructions for that panel.
- Medications to Avoid: No medications need to be discontinued or avoided prior to TPHA testing. Continue all regular medications as prescribed. If patient is receiving treatment for syphilis, TPHA should be collected at baseline before treatment and at follow-up intervals as recommended.
- Special Instructions: Standard venipuncture technique using serum separator tube; No hemolyzed specimens acceptable (may give false results); Blood sample should be clearly labeled with patient identification; Specimens should be transported to laboratory promptly; If delays expected, refrigerate at 2-8°C; Sample stability varies by laboratory, typically 5-7 days refrigerated.

How our test process works!