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Labcorp Oklahoma, Inc.
Test Directory


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Treponemal Antibody Analyzer

Order Name Treponemal AB AN
Test Number: 5500607
Revision Date 11/17/2025
Test Name Methodology LOINC Code
Treponemal Antibody Analyzer
Chemiluminescence Assay 47236-5 
SPECIMEN REQUIREMENTS
Specimen Specimen Volume (min) Specimen Type Specimen Container Transport Environment
Preferred 3 mL (0.6 mL) Serum Clot Activator SST Refrigerated
Instructions Stability: Ambient 3 days. Refrigerated 7 days. Frozen 30 days.
GENERAL INFORMATION
Testing Schedule Mon - Sat 
Expected TAT 1-2 Days  
Clinical Use
Treponemal Antibody (CLIA) Non-Treponemal (RPR) Treponemal Antibody (TPPA) Result Long Name
Non-Reactive Not
Performed
Not
Performed
No laboratory evidence of syphilis. If recent exposure is suspected, submit a new sample for testing in 2-4 weeks
Reactive Non-Reactive Non-Reactive If the Treponemal Antibody detected has a low antibody index (<4.05) by the CLIA method with the absence of confirmation by the TPPA assay it is due to either a patient with a very early Syphilis infection or a false positive. The

Treponemal Antibody assay using the CLIA method is more sensitive than either the Nontreponemal Antibody (RPR) or the TPPA assay, which is also a Treponemal Ab assay. The clinical history is key in determining whether it is a false positive or a very early stage of infection. If a recent exposure is suspected, submit a new sample for testing in 2-4 weeks; however, if the clinical suspicion is low, it is most likely a false positive, and no further testing is needed.
Reactive Reactive Not
performed
Treponemal with Nontreponemal antibodies indicate a current or recent past infection. A thorough clinical evaluation is recommended to access for active signs and symptoms or a history of a recent infection.

Approximately 84-90% of infected patients will remain positive for Treponemal antibody for life and the other 10-16% will be positive for many years. Post-treatment monitoring should be performed using only the Nontreponemal antibody (RPR) assay to evaluate treatment response.
Reactive Non-Reactive Reactive Only Treponemal antibodies detected, thus most likely consistent with past syphilis infection. Clinical evaluation should be performed to identify current signs and symptoms or past history of infection. If past history of treatment is reported, no further management is needed; however, if recent exposure is suspected, submit a new sample for testing in 2-4 weeks. 


Syphilis Testing Algorithm 
Notes The Treponemal Antibody Analyzer screen reactive specimens will reflex to an Non-Treponemal Antibody (RPR) and titer (Test Code 5500605), at additional charge(s). The Non-Treponemal Antibody (RPR) assay is performed to distinguish recent/active from past infection. A Non-Reactive Non-Treponemal Antibody (RPR) assay will reflex a second treponemal assay Treponemal Antibodies, TPPA (Test Code 5501065), at additional charge(s). The presence of maternal Treponemal Antibody (Syphilis specific Antibody) in a baby can be detected up to 15-18 months. Therefore, only a Non-Treponemal antibody (RPR) [5500605] assay will be performed on babies <18 months.
CPT Code(s) 86780 (possible 86780 and 86592)
Lab Section Immunology - Serology