What does the reported titer in a quantitative VDRL test represent?

In the context of the quantitative VDRL test, the reported titer represents the highest dilution of the serum sample that still yields a reactive result. This is a critical aspect of interpreting serological tests, as it indicates the strength of the antibody response present in the serum against the antigens used in the test. A higher titer suggests a stronger immune response, which may be indicative of conditions such as syphilis or other infections that the test is designed to detect.

In quantitative assays, titer levels are determined by conducting serial dilutions of the serum and observing the point at which the test result transitions from reactive to non-reactive. The highest dilution at which the sample still reacts is considered the definitive titer. This provides clinicians with valuable information about the patient's infection status and potentially helps in monitoring treatment efficacy or disease progression.