Lab Test

Syphilis Antibody by TP-PA

TPPA, Treponema pallidum Particle Aggutination

Test Codes


Specimen Collection Criteria

Collect: One Gold-top SST tube. (Minimum Whole Blood: 2.0 mL)

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within two hours of collection. (Minimum Serum: 0.5 mL)

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8°C or 36-46°F). (Minimum Serum: 0.5 mL)

Rejection Criteria

CSF or plasma specimens.

Severely lipemic or hemolyzed specimens.

In-Lab Processing

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Room temperature is acceptable for a maximum of two hours. (Minimum Serum: 0.5 mL)


Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers® with Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers® without Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 1 year

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


Royal Oak Special Testing Laboratory


Sunday – Saturday
Results available within 24 hours of receipt in the Laboratory. 

Reference Range


Test Methodology

Particle Agglutination.


  • Non-reactive: No serologic evidence of exposure syphilis.
  • Reactive: Results suggest previous exposure to Treponema pallidum, the causative agent of syphilis. This test result by itself does not reflect activity or status of infection, treatment outcome, or duration of syphilis infection.
  • Indeterminate: Unable to determine syphilis-specific antibody status. Consider repeat testing in two weeks. 

Clinical Utility

The TP-PA test is used as a follow-up or confirmatory test for specimens that are weakly reactive or reactive in the VDRL assay. This test is also used as a single test in patients suspected of late syphilis when the VDRL test may be negative.

Clinical Disease

Syphilis is a complex systemic illness caused by the spirochete Treponema pallidum. The natural course of syphilis can be divided into five stages. The first stage is an incubation period lasting approximately 3 weeks which is followed by a primary stage characterized by a non-painful skin lesion (chancre) associated with regional lymphadenopathy and early bacteremia. This stage is followed by a secondary bacteremic or disseminated stage accompanied by generalized mucocutaneous lesions and lymphadenopathy. A period of subclinical (latent syphilis) is followed by a late or tertiary stage in a small number of patients. The latent or tertiary stage is characterized by progressive disease involving the ascending aorta and/or the central nervous (CNS), but any organ system can be involved.

Disease Reporting

This is a reportable infection and positive (reactive) results will be reported to the MDCH. For more information on reportable diseases, contact the Beaumont Epidemiology Department at 248-551-4040.


The vast majority of syphilis cases occur in the most sexually active age group (15-30 years old). Increased cases have been seen in heterosexuals. There has been a dramatic increase of syphilis in women and neonates. The increased number of syphilis cases has been attributed to the exchange of sex for drugs, and concomitant infections with HIV.

Incubation Period

Average incubation period is 21 days (range of 3-90 days).


Syphilis is transmitted by sexual contact, by passage through the placenta (congenital syphilis), by kissing, by transfusion of fresh human blood, or by accidental direct inoculation (e.g., needle prick, or when handling infected clinical material). 


  1. Tramont,E. Treponema Pallidum (Syphilis) Mandell, G., Bennett, J., Dolin. R.(eds.), Principles of Infectious Diseases 4th edition New York, N.Y. 1995; 2117-2133.
  2. American Public Health Assoc. A Manual of Tests for Syphilis. Larsen, S.A., Pope, V., Johnson, R.E., Kennedy Jr., E.J. (eds.), 9th edition, Washington, D.C. 2000.  

CPT Codes

LOINC:  24312-1


Last Updated


Microtainer® and Vacutainer® are registered trademarks of Becton, Dickinson and Company.
UroVysion® is a registered trademark of Abbott Laboratories. ThinPrep® is a registered trademark of Hologic, Incorporated.