ANA (antinuclear antibodies): ANA testing is a screening tool used to detect the presence of antibodies that target the cell nucleus. It is a broad test that can indicate the possibility of an autoimmune condition, as many autoimmune diseases are associated with the production of ANA. Rheumatoid factor: Rheumatoid factor is an antibody directed against the Fc portion of immunoglobulin G (IgG). It is primarily used in the diagnosis of rheumatoid arthritis (RA). Elevated levels of rheumatoid facto