One of the most common consult of a rheumatologist is the evaluation of a patient with a positive ANA. A lot of my colleagues complain that many are being checked without proper reasons. I concur with them that we need to do a much better job at explaining what an ANA is, why we would be checking this antibody and what it actually means to have a positive test. I hope to clarify this question in this blog post.
What is ANA?
ANA stands for Anti-Nuclear Antibody. It is an autoantibody (an antibody produced by the body’s own immune system) that is directed against proteins found in the nucleus of cells and can appear in autoimmune disorders. The ANA can attach to the nucleus of cells in the body, causing damage and inflammation. In certain autoimmune diseases, the body mistakenly produces ANAs, which can attack healthy cells and tissues.
However, a positive ANA result alone does not necessarily mean that the patient has an autoimmune disease.
When should we check for an ANA?
This is a very important_and probably the most important_ point. The most common mistake that physicians, Physicians assistants and Nurse practitioners make is to order an ANA when they do not know what is happening to a patient. In general, and particularly in rheumatology, each test ordered should have a reason: either to confirm or rule out a diagnosis, before/after a treatment to make sure it is safe, or for prognostic status. So, if the only symptom is fatigue, without any other symptoms, ANA should not be checked.
So, when should we order and ANA? We use ANA to help us with diagnosing auto-immune diseases. To help diagnose autoimmune diseases. A positive ANA test result indicates that the patient has antibodies in their blood that are targeting their own cells. Other tests and a thorough physical examination are usually needed to make a diagnosis.
What does it mean to have a positive ANA?
There is ANA and there is ANA
It's important to note that ANA tests are not always accurate. A direct ANA test, for example will only test for ANA and has a lot of false positive. We need the level as well as the pattern of the ANA.
Let’s review quickly how an ANA is being tested. The labs screens the sample initially at a single dilution, usually 1:40 or 1:80 and if there is persistent evidence of positive ANA, the lab continues to dilute until the sample returns negative (starting at 1/40 then 1/80, then 1/160, 1/320, 1/640, 1/1280, 1/2560, 1/5120 etc). The higher the dilution, the more ANA the sample has.
In addition to the titers of the ANA, we also need to look at the pattern.
There are several different types of ANA patterns (see image) that can be detected on a laboratory test. These patterns are determined by how the antibodies bind to the cell nucleus and can provide important clues as to which autoimmune disease a patient may have. Indeed, a positive ANA at 1/40 is most likely the equivalent of a negative test if its pattern is homogenous, but could be related to Sjogren or other autoimmune disorder if speckled.
What if the ANA is really positive?
A positive ANA result can be associated with a range of autoimmune diseases. Some of the most common autoimmune diseases associated with a positive ANA result include but are not limited to Systemic Lupus Erythematosus (SLE), Sjögren's Syndrome, Scleroderma or
Polymyositis and Dermatomyositis to name a few. You can learn more about these conditions in our other blog posts (if they have not yet been discussed, follow the blog as it will be soon!).
Other Autoimmune disorders, such as Hashimoto, a thyroid disorder or autoimmune hepatitis, a liver condition can also be associated with a positive ANA.
Finally, a positive ANA result alone is not enough to diagnose an autoimmune disease. Other tests, such as blood tests and imaging studies, are often needed to confirm a diagnosis. If you have a positive ANA result and experience symptoms such as fatigue, joint pain, skin rashes, or difficulty swallowing, it's important to see a rheumatologist for further evaluation and management. Early diagnosis and treatment can help manage symptoms and improve quality of life.
In conclusion.
ANA testing is an important tool in the diagnosis of autoimmune diseases, but it's not foolproof. False negative and false positive results can occur. Overall, unless you have no symptoms, your ANA is low titer and homogenous, chances are you will need a specialized evaluation by a rheumatologist to gather more evidence of what your symptoms are and which disease you may indeed have.
If you are in Colorado, UnabridgedMD in Rheumatology is currently open to new patients. We have a diagnostic package that can help you get the response you need. Contact us at info@unabridgedMD.com.
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