Syphilis Total Antibodies with Reflex Confirmation

Label Mnemonic:	SYPHT
Epic code:	LAB8631
Order form:	Laboratory Requisition
Supply order:	Supply Order Form
Billing:	Billing Policies
CPT code:	86780 (Syphilis total antibodies) 86592 (RPR - if performed as reflex) 86593 (RPR titer - if performed as reflex) 86780 (TPPA - if performed as reflex)

Specimen(s):

Serum

Collection Medium:

BD Gold SST 5 mL Vacutainer

Minimum:

5 mL serum from a BD Gold SST tube

Testing Schedule:

24 hrs/day, 7 days a week, including holidays.

Turn Around Time:

2 hours (upon receipt in laboratory)

Reference Range:

Negative

Interpretive Data:

The syphilis total antibodies (IgG + IgM) screen is a new method 
relative  to the RPR (rapid plasma reagin). The RPR detects non-treponemal 
antibodies (cardiolipin, cholesterol, and lecithin), whereas the the 
newer serology test detects IgG and IgM antibodies to T. pallidum 
proteins. The new approach to syphilis is termed 'reverse algorithm' in 
that RPR is not done as first test (traditional algorithm) but as the 
confirmation (i.e., reverse of the traditional algorithm). A negative 
syphilis total antibodies means that past and present syphilis infection 
is unlikely. A positive syphilis total antibodies, which can indicate a 
past or present infection, reflexes automatically to RPR. If there is 
discrepancy between syphilis total antibodies and RPR, TPPA (T. 
pallidum particle agglutination) is additionally performed. For 
patients  who have been treated for syphilis, RPR titers should be 
followed (orderable as Syphilis Treatment Follow-up (RPR with Titer) in 
Epic.  Successful treatment is generally indicated by a 4-fold or more 
reduction in RPR titer (e.g., 1:32 to 1:8).

The interpretation is as follows using CDC guidelines:


  
    Syphilis Total
 Antibodies
    RPR
    TPPA
    Interpretation
  
  
    Negative
    Not done
    Not done
    Syphilis infection 
unlikely
  
  
    Positive
    Positive
    Not done
    Syphilis – recent 
infection likely
  
  
    Positive
    Negative
    Positive
    Syphilis – past or 
present infection
  
  
    Positive
    Negative
    Negative
    Infection unlikely – 
false positive syphilis   
total antibodies
  



As mentioned above, positive syphilis total antibodies can occur with 
past or present infection.

There are several advantages of the reverse algorithm:
•Rapid turnaround time for syphilis total antibodies
•Avoids the false positives seen with RPR in autoimmune
 disease (e.g., lupus), infectious mononucleosis, viral pneumonia,
 and non-syphilis treponemal diseases (e.g., yaws)
•Detects early primary and latent infection that may be missed
 with traditional RPR screening.

Some key points to remember with the reverse algorithm:
•Syphilis total antibodies can persist for many years. A
 positive result does not necessarily indicate active disease. In
 patients with positive syphilis total antibodies, the RPR provides
 information on active versus past infection.
•For assessing treatment efficacy in patients who have been
 treated for syphilis, "Syphilis Treatment Follow-up (RPR with Titer)"
 should be ordered. Successful treatment is generally indicated by a
 4-fold reduction in RPR titer (e.g., 1:32 to 1:8).
•The syphilis total antibodies can have false positives. These
 will be indicated by negative RPR and TPPA confirmation. Given the
 generally low prevalence of syphilis in Iowa, false positives will
 be a significant fraction of positive screening test results
 regardless of testing method used.
•Iowa Department of Public Health will investigate positive
 syphilis total antibodies results only after confirmatory testing
 results are available. The full set of results guides investigation
 and follow-up.

Comments:

New assay (switch from syphilis IgG to syphilis total antibodies) introduced April 3, 2018.

Positive syphilis total antibodies results are reflexed automatically to RPR. If syphilis total antibodies and RPR results are discrepant, TPPA is additionally performed. For those samples that reflex to RPR testing, RPR assay interference resulting in false positive results may occur with cross-reacting antibodies from patients diagnosed with systemic lupus erythematosus, malaria, autoimmune disease, and viral pneumonia. RPR results should be interpreted in conjunction with patient history, risk factors, and other syphilis testing.

Assay updated with increased tolerance to biotin on 3/7/23.

Test Limitations:

The assay is unaffected by icterus < 66 mg/dL, hemolysis (Hb < 500 mg/dL), lipemia < 2000 mg/dL)and biotin <1200 ng/mL.

Methodology:

Electrochemiluminescence Immunoassay

Sample Processing:

Centrifuge at a speed and time necessary to get barrier separation of plasma/serum and cells within 1 hour of collection. Send specimen in original tube. Do Not transfer to another tube.
Each sample must be labeled with at least TWO full patient identifiers (First/Last Name & DOB are sufficient for non-UIHC affiliated clients) to avoid sample rejection/delays.

Sample Storage:

Refrigerate.

Transport Instructions:

Place labeled specimen into zip-lock type biohazard bag; seal bag.
Place completed requisition into outside pocket of bag.
Transport in cooler with refrigerated coolant packs.

CPT Code:

86780 (Syphilis total antibodies)
86592 (RPR - if performed as reflex)
86593 (RPR titer - if performed as reflex)
86780 (TPPA - if performed as reflex)

See Additional Information:
Biotin Interference with Immunoassays

Syphilis Total Antibodies	RPR	TPPA	Interpretation
Negative	Not done	Not done	Syphilis infection unlikely
Positive	Positive	Not done	Syphilis – recent infection likely
Positive	Negative	Positive	Syphilis – past or present infection
Positive	Negative	Negative	Infection unlikely – false positive syphilis total antibodies