Syphilis Total Antibodies with Reflex Confirmation
Label Mnemonic: | SYPHT |
Epic code: | LAB8631 |
Downtime form: | A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery |
Chemistry
6240 RCP
356-3527
6240 RCP
356-3527
Specimen(s):
Serum
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 |
RPR |
TPPA |
Interpretation |
Negative |
Not done |
Not done |
Syphilis infection |
Positive |
Positive |
Not done |
Syphilis – recent |
Positive |
Negative |
Positive |
Syphilis – past or |
Positive |
Negative |
Negative |
Infection unlikely – |
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.
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
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)
86592 (RPR - if performed as reflex)
86593 (RPR titer - if performed as reflex)
86780 (TPPA - if performed as reflex)