The RPR test is short for Rapid Plasma Reactin Ring Card Test, which is a serological test for screening syphilis. It is often used by physicians as a preliminary diagnosis of syphilis because it is easy to perform, rapid, has good sensitivity and specificity, and can be applied to screen large populations. Anyone with a positive RPR should have a further confirmatory test to confirm or exclude syphilis. The RPR test checks for reactive hormones in the body. The source of the reactive hormone is still controversial. Most people believe that it is a lipid-like component of the human body that has been damaged by syphilis spirochetes and cleaved from the tissues, which binds to the proteins of syphilis spirochetes and becomes an antigen that stimulates the body to produce anti-lipid-like antibodies, or reactin. Syphilis spirochetes destroy tissues to make the body produce reactin, and other processes that destroy the body can also produce reactin, so syphilis patients with positive RPR test, but RPR-positive people are not always syphilis. RPR can be false positive in certain physiological states of the body, such as pregnancy, old age, or when suffering from some other diseases; RPR can also be positive when a person has acute infectious diseases, such as rubella, chickenpox, viral hepatitis, upper respiratory tract infection, tuberculosis, pneumonia, leptospirosis, subacute bacterial endocarditis, etc.; many chronic diseases, such as rheumatoid arthritis, rheumatic heart disease, leprosy, liver cirrhosis, tuberculosis, conjunctivitis, etc. Many chronic diseases, such as rheumatoid arthritis, rheumatic heart disease, leprosy, liver cirrhosis, polyarteritis nodosa, autoimmune hemolytic anemia, dry syndrome, chronic nephritis and heroin addiction, can also be positive for RPR. Therefore, syphilis cannot be diagnosed on the basis of positive RPR alone, but patients should be examined comprehensively and followed up closely. In addition, there are more technical requirements for the operation of the RPR test, and some small hospitals and clinics may not be able to meet the requirements and affect the test results. Syphilis is a venereal disease with a variety of symptoms and serious hazards. The diagnosis of syphilis should be based on a comprehensive analysis of the history of sexual contact, clinical manifestations and laboratory diagnosis, and cannot be determined solely by laboratory test results. For those who are positive for RPR test, serological tests with syphilis spirochetes as antigen, such as syphilis spirochete hemagglutination test and syphilis spirochete fluorescence antibody uptake test, are also needed to confirm the diagnosis.