A positive ANA is a positive antinuclear antibody, which is a screening test for connective tissue disease and is a representative test for autoantibodies. Positive anti-nuclear antibodies usually indicate the possibility of connective tissue disease. This is because low potency anti-nuclear antibodies can occur in normal people. In addition, infectious diseases, such as tuberculosis and infective endocarditis, can also be associated with low potency anti-nuclear antibodies. Therefore, only positive anti-nuclear antibodies of high potency are often clinically significant. And it is mostly seen in connective tissue diseases, such as rheumatoid arthritis, systemic lupus erythematosus, dry syndrome, polymyositis, dermatomyositis, scleroderma, mixed connective tissue diseases and many other diseases. When the antibody is positive, it must be combined with clinical symptoms and other testing indicators to make a comprehensive analysis.