Rapid Plasma Reagin Screen with Reflex to Titer, Serum

Casandra

Casandra Test Code MC99812Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID RRPRSCPT Codes 86592, 86593, 86780

Rapid Plasma Reagin Screen with Reflex to Titer, Serum

Clinical Use

Use

This test aids in the diagnosis of infection with Treponema pallidum and is used for rapid plasma reagin testing following a positive treponemal antibody test. It is important in the diagnosis and follow-up of syphilis treatment. The RPR is a macro-flocculation test which, if positive, indicates the presence of nonspecific antibodies in the patient's serum suggesting active syphilis. In the context of syphilis testing, the RPR is used as part of the reverse syphilis screening algorithm to confirm the presence of infection after a positive syphilis IgG result. However, RPR is not useful as a screening or confirmatory test for blood donor specimens, due to its limited specificity in these contexts.

Special Instructions

The test is only orderable as a reflex and is not available as a standalone, direct order. A positive RPR screen will result in performing an RPR titer at an additional charge. If the RPR screen is negative, then syphilis antibody Treponema pallidum particle agglutination testing will be conducted at an additional charge. This reflects the reverse algorithm employed by Mayo Clinic Laboratories for syphilis screening.

Limitations

The test may produce false negatives in severely immunosuppressed patients, such as those with AIDS. Serologic tests might also be negative in very early cases of primary syphilis or untreated late or latent syphilis. Additionally, this test is nonspecific and cannot differentiate between active and past treated syphilis if using treponemal assays. The presence of antibodies can persist even after effective treatment, thus interpretation in the context of clinical and historical data is crucial for accurate diagnosis.

Test Details

FDA Approved