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Syphilis serologic testing

Item Value
Approval req'd? No
Available Stat? No
Test code
Test group Syphilis
Container type
Sample type
Normal range
Synonyms MHA-TP; FTA-Abs; T. pallidum; MHATP; Syphilis; Treponema pallidum; VDRL; RPR
Additional information Non-treponemal tests (RPR; Rapid Plasma Reagin and VDRL; Veneral Disease Research Laboratory) are used as screening tests in patients with suspected syphilis. Non-treponemal antibody titers correlate with disease activity and usually become non-reactive over time after successful treatment. However, low titers may persist for many years even in successfully treated patients.

Treponemal specific tests (FTA-ABS; Fluorescent Treponemal Antibody Absorption and MHA-TP; Microhemagglutination Assay-Treponema pallidum) are used to confirm positive screening tests and are performed automatically with an additional charge unless the laboratory is requested to omit this reflex testing. Treponemal specific tests typically remain reactive for the life of a patient regardless of treatment or activity and are not reported.

The VDRL test is the only serological assay which is approved for use in CSF. The VDRL is highly specific for neurosyphilis, and a positive result can typically be considered diagnostic. Due to its low sensitivity however, a non-reactive result cannot be used to rule out neurosyphilis. In patients suspected of neurosyphilis but with a non-reactive VDRL result, the FTA-ABS test may be useful in some cases. The FTA-ABS test has high sensitivity but is nonspecific with a high rate of false positive results. Therefore, a non-reactive test may be useful in ruling out neusosyphilis, but a positive test cannot be considered diagnostic.


Birnbaum NR, et al. Resolving the common clinical dilemmas of syphilis. American Family Physician 1999; 50: 2233-2240

Sexually transmitted disease treatment guidelines 2002. MMWR May 10, 2002. Volume 51, No. RR-6.
Last Updated 8/24/2011 12:28:13 PM
Entry Number 881
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