Test Details: An ANA test is used to help diagnose autoimmune disorders such as: Systemic lupus erythematosus (SLE), the most common type of lupus. Lupus is a chronic (long-lasting) disease that affects many parts of the body including the joints, skin, heart, lungs, blood vessels, kidneys and brain. It helps in detecting Antibodies to 17 Extractable Nuclear Antigen.