The rapid plasma reagin (RPR) test has several useful purposes. It is used to screen asymptomatic
The RPR is a simplified version of the other nonspecific screening test for syphilis, the VDRL test. The RPR card test uses a mixture of reagin and carbon particles to which a patient's serum is added. Flocculation, or clumping, of the particles is read as a "reactive" or positive test. The test can be quantitated by examining serial dilutions of serum. A difference of two dilutions is required to demonstrate a significant difference between two tests.
JUDITH E. WOLF
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Wolf, J. (1997). "Syphilis." In Current Diagnosis, 9th edition, eds. R. Conn, W. Borer, and J. Snyder. Philadelphia, PA: W. B. Saunders.