RPR Test – Rapid Plasma Reagin

The Rapid Plasma Reagin (RPR) test is a blood screening test used to detect syphilis, a sexually transmitted infection caused by the bacterium Treponema pallidum. RPR is a non-treponemal test that detects antibodies (reagin) produced in response to cellular damage from syphilis infection. It is commonly used for initial screening and for monitoring treatment effectiveness.

1. What Is the RPR Test?

• RPR is a non-specific test that detects reagin antibodies, which are not directed against the bacterium itself but against substances released by cells damaged by the infection.

• It is often used in combination with a specific treponemal test (e.g., FTA-ABS or TPPA) to confirm syphilis diagnosis.

2. Why Is the RPR Test Performed?

This test is used to:

• Screen for syphilis in individuals with symptoms or at risk of infection.

• Monitor response to syphilis treatment (a falling titer indicates successful therapy).

• Screen pregnant women, blood donors, or individuals with other sexually transmitted infections (STIs).

3. Interpreting RPR Results

🔹 Reactive (Positive) RPR:

• Suggests possible syphilis infection.

• Requires confirmation with a treponemal-specific test to confirm diagnosis.

• The test result is usually reported as a titer (e.g., 1:8, 1:64), which can be tracked over time to assess treatment response.

🔹 Non-reactive (Negative) RPR:

• Indicates no evidence of current syphilis infection.

• Early or late-stage syphilis may yield false-negative results — further testing may be needed if clinical suspicion is high.

4. What Can Affect RPR Test Accuracy?

• False positives may occur with pregnancy, autoimmune disorders (e.g., lupus), certain viral infections, or drug use.

• False negatives may occur in early syphilis, late syphilis, or due to the prozone effect (excess antibodies).

5. How Is the Test Performed?

• A blood sample is drawn from a vein.

• The test is typically performed in a lab or clinical setting with results available within hours to a few days.

6. When to See a Doctor

🚨 Consult your healthcare provider if you:

• Have had unprotected sex or exposure to a partner with syphilis.

• Experience symptoms such as sores, rash, or swollen lymph nodes.

• Are pregnant or planning pregnancy and need STI screening.

🔹 Key Takeaways

✅ The RPR test is a widely used screening tool for syphilis.

✅ Positive results require confirmation with specific treponemal tests.

✅ RPR titers are useful for diagnosing and monitoring treatment of syphilis.