Definition

Describes a laboratory test result that shows the presence of a specific marker, usually an antibody, in the blood. Antibodies are proteins made by the body’s immune system in response to a foreign substance or microorganism, such as a virus. A seropositive test result usually means that a person has been exposed to or infected with a virus or other infectious agent and has made antibodies against it. Sometimes antibodies are made against the body’s own tissues. In that case, a seropositive test result means that a person has antibodies or other markers for a certain disease, such as an autoimmune disease. More testing may be needed to make a diagnosis or to make sure a seropositive test result is correct.