How does a temperature of 20°C affect VDRL and RPR test results?

A temperature of 20°C can adversely affect the outcomes of the VDRL (Venereal Disease Research Laboratory) and RPR (Rapid Plasma Reagin) tests, leading to weakened reactions and an increased likelihood of false negatives. These tests rely on antigen-antibody interactions that are optimal at higher temperatures, typically around 30–37°C. When the testing environment is at a lower temperature, the antigen-antibody interactions may be diminished, resulting in reduced sensitivity of the test. Consequently, this can lead to a higher risk of failing to detect syphilis, as the reaction may not be strong enough to produce a positive result.

Higher temperatures serve to enhance the reactivity of the tests, thus improving their reliability and the likelihood of obtaining accurate results. Therefore, conducting these tests at a temperature around room temperature (20°C) is not ideal, as it impacts the performance and can compromise the reliability of the diagnostic testing for syphilis.