An antinuclear antibody (ANA) test looks for antinuclear antibodies in a person’s blood. ANAs are a type of antibody called an autoantibody, and, like other antibodies, they are produced by the immune system. While healthy antibodies protect the body from pathogens like viruses and bacteria, autoantibodies cause disease by mistakenly attacking healthy cells and tissues.

ANA testing requires a blood sample, which is typically taken from a patient’s arm. Testing for ANAs is used to help diagnose and determine the type of autoimmune disorder affecting a patient.