the ana (antinuclear antibody. ) is a blood test that when positive is associated with autoimmune diseases the prototype of which is lupus (sle). a + test by itself (titer >1:160) does not define sle since one needs to have the signs and symptoms associated with the disease. thus the test has to be interpreted in the context of the individual as evaluated by the doctor. the test can be falsely + i. e. + in a patient who does not have the disease (about 10%) or + in other conditions such as scleroderma sjogren's syndrome to name a few. if the test is negative the likelihood is that you do not have lupus since there are way fewer false negatives than false positives. if your doctor however thinks that you do have lupus (by signs and symptoms) despite the negative ana some other tests may be done by your md. finally the ana test is not done to follow the activity of the disease so it is unneccessary to continue to repeat it. .
what is an ana test?