The Antinuclear Antibody Test: What It Means
How does your doctor use the ANA result?
The doctor will view your ANA and other lab results in light of your history and physical exam to determine if there is sufficient evidence to diagnose a specific illness. None of the connective tissue (joints, tendons, cartilage, collagen, muscles and skin) diseases has specific diagnostic tests. Diagnosis is therefore based on meeting certain criteria for the disease which are based on the symptoms you have had, your physical examination, and your blood tests. In systemic lupus, eleven criteria were developed for research purposes but are frequently used to diagnose lupus.
Usually, physicians do not make a diagnosis of lupus unless they determine that the patient has at least four criteria. If only two or three criteria are met, then there may not be enough evidence to support a diagnosis of lupus. Since not all of the criterion are black and white, a physician may sometimes be uncertain whether a patient meets a particular criterion or not. This adds to the difficulty in diagnosis.
Furthermore, if another disease or condition can explain the presence of the criterion in a patient, then it may not indicate lupus. Therefore, it's possible to meet four criteria, and not have lupus.
Why does it take so long to know "for sure"?
If your ANA is positive and you have many symptoms, your doctor may suspect some kind of connective tissue disease. If at that time there aren't enough symptoms and lab work to satisfy the criteria for any one disease, then it is impossible to specify a particular disease or to confirm a diagnosis.
Lupus tends to develop slowly and evolve gradually over time. Many-or even most-people who have just a few of the criterion for lupus never develop this or any other connective tissue disease, and either improve or continue as they are.
Awaiting a diagnosis can be frustrating. If only one or two criteria are satisfied, it's similar to a picture that's only partially developed. No one looking at that picture can accurately identify it. Nor can they predict if it will develop into anything that can be identified, how long it will take before it is developed enough to identify, or if it will develop further at all!