Frequently Asked Questions (FAQs)
ANA is useful in the diagnosis of systemic rheumatic diseases such as SLE, mixed connective tissue disease (MCTD), undifferentiated connective tissue disease, Sj-gren syndrome, scleroderma (systemic sclerosis), polymyositis and others. Some patients, without clinical evidence of an autoimmune disease or a systemic rheumatic disease, may have a detectable level of ANA. This finding is more common in women than in men and the frequency of detectable ANA in healthy women aged above 40 may approach 15%-20%. ANA may also be detectable following viral illnesses, in chronic infections or in patients treated with many different medications. Drugs that may cause positive results include carbamazepine, chlorpromazine, ethosuximide, hydralazine, isoniazid, mephenytoin, methyldopa, penicillins, phenytoin, primidone, procainamide, and quinidine.