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Lab Manual for UCSF Clinical Laboratories

Lab Manual for SFGH

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Item Value
Available Stat? No
Test code RPR; RPRP (prenatal); RPRC (cord blood)
Performed by? Microbiology
Sendout? no
Price range $
In House Availability Monday - Friday
Principle This is a non-treponemal antibody test for syphilis, which is performed with a cardiolipin-lecithin antigen prepared in suspension with carbon particles. The test detects "reagin", antiphospholipid antibodies present in serum from syphilitic persons and occasionally in serum of persons with other acute or chronic conditions. When a specimen contains antiphospholipid antibody, flocculation occurs with coagglutination of the antigen coated carbon particles. This flocculation is read macroscopically. Titers will be performed on all RPR reactive specimens.
Interpretation The RPR is a useful screening test which is of diagnostic significance when correlated with clinical information. It can be semiquantitated; titers generally rise with disease activity and fall with effective therapy, thus being useful in judging effectiveness of therapy. The RPR generally becomes reactive in untreated syphilis at 4-6 weeks after infection or 1-3 weeks after the chancre appears.

Using cardiolipin type antigens, biological false positive reactions have been reported in diseases such as infectious mononucleosis, leprosy, malaria, lupus erythematosus, vaccinia and virus pneumonia. In pregnancy, several reports indicated the occurrence of false positive reactions. Narcotic addiction and autoimmune diseases also may give false positive reactions. Pinta, yaws, bejel and other treponemal diseases produce positive reactions in this test but should not be considered false positive reactions.

If the patient does not have a prior history of syphilis, specimens found to be reactive by the RPR screening test are then tested by the more specific, TP-PA (Treponema pallidum particle agglutination) treponemal antibody test.
Negative RPR results may occur in sera of patients with large amounts of reaginic antibody which may occur in secondary syphilis. If this is suspected, request further dilution of serum and retesting. The RPR is generally negative in late syphilis. If late syphilis is suspected, also request the TP-PA test. Once positive, the TP-PA test will remain positive for life.

Some patients have persistent elevation of the RPR in spite of apparently adequate treatment. This may be due to inadequate treatment, re-infection or biological false positive (BFP) reactions. The BFP reaction may occur in early HIV infection due to the production of polyclonal antibodies.
Container type gold top gel tube
Amount to Collect 3 mL
Sample type Blood
Normal range nonreactive
Synonyms Rapid Plasma Reagin (Test for Syphillis);Syphilis Testing;
Additional information REQUISITION: Blood/Serum - Main Laboratory
References 1. Larsen, S.A. and Creighton ET. Rapid Plasma Reagin 18-mm Circle Card Test. Chapter 10, pp 193-207. In: Larsen SA, Pope, V., Johnson, R.E., and Kennedy, Jr., E.J., Eds. A Manual of Tests for Syphilis, 9th Ed. Amer. Public Health Assoc., Washington, DC, 1998.

2. Mandell GL, Bennett JE, and Dolin R., Eds. Principles and Practice of Infectious Diseases, 6th ed., Churchill Livingstone, Inc. New York, 2005

3. Ng, VL. B-Lymphocytes and autoantibody Profiles in HIV Disease. Clin Rev Allergy and Immunology 14, 367-384. 1996.
CPT coding 86592
Last Updated 11/12/2008 11:24:35 AM
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