RPR | Syphilis Detection

RPR (Rapid Plasma Reagin) test is a non-specific serological blood test used for the detection and monitoring of syphilis infection. The test helps to assess if the human body is responding to Treponema pallidum – the bacterium causing syphilis. The RPR test is most often performed alongside specific syphilis tests, such as TPHA or FTA-ABS.

A positive RPR reaction usually occurs 4-6 weeks after infection, when the body begins to produce reagin – antibodies against lipid components that appear with tissue damage due to treponemal infection. The highest reagin titer is determined in the second stage of syphilis, and then the titer gradually decreases, allowing the RPR to be used for monitoring treatment effectiveness.

It is important to know that the RPR test is not specific only to syphilis, and therefore may be falsely positive in other conditions: pregnancy, infections (e.g., Lyme disease, mononucleosis, toxoplasmosis), autoimmune diseases (collagenoses, vasculitis), or even after vaccination.

Test principle: The test is based on the detection of non-specific antibodies (reagins) that react with the cardiolipin antigen. Results are presented as reactive (positive) or non-reactive (negative), and in the case of a positive result, the titer is also indicated.

Recommendations:

• Recommended when syphilis is suspected or if there have been risky sexual contacts.
• Useful for monitoring treatment effectiveness – a decrease in titer indicates successful treatment.
• Prescribed alongside specific tests (e.g., TPHA) to confirm the diagnosis.
• Can be applied during pregnancy, in cases of donation, or before surgeries.
• No specific preparation is needed for the test, but the clinical context must be evaluated to rule out false positive results.