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rapid plasma reagin (RPR)

Indications: - syphilis - pityriasis rosea* * resembles secondary syphilis Principle: - nontreponemal serologic tests used in the diagnosis of syphilis include: - VDRL reagin slide - rapid plasma reagin circle card (RPR) - unheated serum reagin (USR) - toluidine red unheated serum test (TRUST) - all of these tests are based upon detection of immunoglobulin, IgG or IgM (reagin) directed against non treponemal antigens - all nontreponemal assays utilize an active phospholipid (cardiolipin) antigen combined with lecithin & cholesterol in a colloidal particle Clinical significance: Sensitivity (serum): - primary: 77-100% - secondary: 100% - tertiary: 73% False positives: (titers rarely exceed 1:8) 1) connective tissue diseases a) lupus erythematosus b) rheumatoid arthritis 2) infections a) infectious mononucleosis b) leprosy c) malaria d) Mycoplasma pneumonia 3) pregnancy 4) addiction 5) some immunizations 6) advanced age (10% of patients > 70 years of age) Other antibodies found in patients with false + RPR: 1) antinuclear 2) antithyroid a) anti-thyroid peroxidase b) anti-thyroglobulin 3) antimitochondrial 4) rheumatoid factor 5) Donath-Landsteiner antibody (paroxysmal cold hemoglobinuria) 6) cryoglobulins A positive RPR should be followed up with confirmatory testing: - treponemal serologic test for syphilis Specimen: - serum, plasma - RPR is NOT suitable for use with CSF Methods: - antigen is mixed with charcoal in the RPR to make clumping of lipids by plasma antibody macroscopically visible - the addition of choline chloride to the antigen eliminates the need to heat the serum before testing

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syphilis

General

nontreponemal serologic test for syphilis reagin

References

  1. Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 1186
  2. Clinical Guide to Laboratory Tests, 3rd ed. Teitz ed., W.B. Saunders, 1995
  3. Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 733, 734, 738
  4. Medical Knowledge Self Assessment Program (MKSAP) 17, American College of Physicians, Philadelphia 2015
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  6. Mini Panel of 2 tests: T.Pallidum (VDRL) CSF Reflex . Treponema pallidum (VDRL) Titer, CSF Laboratory Test Directory ARUP: 50206
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