This test is used to screen for syphilis, and to monitor the course of treatment.
PLEASE NOTE: ALL RESULTS AND INFORMATION PROVIDED BY HEALTH eLABS ARE INTENDED FOR GENERAL HEALTH INFORMATION PURPOSES ONLY. AS SUCH THEY ARE NOT A SUBSTITUTE FOR PROFESSIONAL MEDICAL ADVICE OR A MEDICAL EXAMINATION, AND SHOULD NOT BE USED TO DIAGNOSE, TREAT, PREVENT OR CURE ANY DISEASE, SYNDROME, OR CONDITION WITHOUT THE SUPERVISION OF A LICENSED PHYSICIAN.
This test can also be purchased as part of our Sexually Transmitted Infections panel.
NOTE: This test is used to screen for the presence of the bacteria that cause syphilis. It should not be used to confirm an infection of syphilis. For those who need testing to confirm whether they have been infected, please visit the Syphilis (FTA Confirmation) page.
PREPARATION: No fasting or other special preparation is needed for this test.
What does this test do?
This test checks for the presence of antibodies circulating in the bloodstream that may indicate a syphilis infection.
Why is this important?
Syphilis is a sexually transmitted infection that, if not properly treated can result in damage to the heart, brain, skin, and bones. It can even cause death. These complications can take years or even decades to develop, and typically progress through four stages: primary, secondary, latent, and tertiary.
Typical symptoms of syphilis during the primary stage include a painless skin ulcer called a chancre, that forms at the site where the bacteria first penetrated the skin (usually around the genitals or groin).
The secondary stage occurs a few months after infection and is characterized by vague, non-specific symptoms such as fever, headache, sore throat, a decreased appetite, generalized body aches and pains, and a rash. If the rash involves the palms of the hands and the soles of the feet, then this type of pattern is relatively specific to syphilis. In fact, syphilis has been called “the Great Imitator” because these types of symptoms often mimic those associated with many other diseases.
During the latent stage – which may last years or even decades – most cases of syphilis show no symptoms, except for occasional relapses of the non-specific secondary phase symptoms.
Eventually an untreated infection may progress to the tertiary stage of syphilis, and can result in devastating damage to the liver, bones, testicles, heart, and blood vessels. Tertiary syphilis can also affect the central nervous system by causing dementia, and stroke.
Syphilis is caused by a microorganism called treponema pallidum (t. pallidum), a member of an extremely specialized class of bacteria called spirochetes. These microbes are notoriously difficult to detect on testing modalities, but once found they are relatively easy to kill with antibiotics.
Unlike many other organisms that have become resistant to penicillin, treponema pallidum remains sensitive to the drug so the treatment of most cases of syphilis remains straightforward. During its primary and secondary stages a single injection of an appropriate dose of penicillin will cure the disease, while those in the latent and tertiary stages of syphilis need three injections, given over a three week period. For those who are allergic to penicillin other oral antibiotics can be used, but with diminished success.
Quite unlike its treatment, however, the diagnosis of syphilis remains difficult even to this day, and many different screening tests have been developed over the years to detect it. If a screening test for treponema pallidum (such as the RPR) is positive, then a secondary test is used to confirm the presence of infection within the body.
That is what this test, the Rapid Plasma Reagin (RPR), is for. It does not detect antibodies against the actual organism that causes syphilis, but rather checks for non-specific antibodies to several substances released by cells when they are damaged by t. pallidum.
The RPR test is one of the most commonly used screening tests for syphilis, as it is extremely sensitive – it can detect 70-80% of patients with primary syphilis, and 99% of those with secondary syphilis.
What do the results mean?
A negative RPR screening test suggests that there is no current syphilis infection, but this is not 100% guaranteed. The RPR test can be falsely negative in all stages of syphilis, especially the early primary stage when the infection is still incubating. If an initial test is negative and clinical signs or symptoms of syphilis develop, then repeat testing should be considered under a physicians’ guidance.
A positive RPR result is an indicator of a syphilis infection; however a number of other conditions may cause the RPR to be falsely positive. These include systemic lupus erythematosus, leprosy, brucellosis, atypical pneumonia, typhus, or pregnancy. Other diseases caused by spirochete bacteria similar to t. pallidum – such as yaws and pinta – may result in a falsely positive RPR as well.
That being said, if an RPR result does come back positive then an additional test will be performed (at no additional charge) to measure the actual quantity of antibodies circulating in the blood stream. This test is called an RPR titer, and is used to monitor treatment by repeating it at regular intervals to track the progress of the disease. This is important because even after any symptoms go away, the t. pallidum bacteria can still hide within the body and lead to complications.
In the case of a positive RPR test, additional, confirmatory testing is recommended by health authorities including the Centers for Disease Control (CDC). One of the most common tests used to confirm the presence of t. pallidum infection is the Fluorescent Treponemal Antibody, or (FTA Confirmation) test.
A positive RPR result must be taken very seriously, and given the potentially devastating and irreversible complications of syphilis if left untreated, should be followed up with your physician promptly for further evaluation, treatment, and guidance.