What does a positive antinuclear antibody mean?
Very often I have patients who come in to my office concerned that they
have an autoimmune condition such as lupus because they were found to
have a positive antinuclear antibody (ANA) on laboratory testing. As a
rheumatologist, it’s my job to find out if that positive ANA has
any clinical significance. As a patient, it is key to understand what
exactly an ANA means. So let’s break it down.
Antibodies are proteins that are made in large amounts by the immune system.
They are essential in recognizing and fighting infectious organisms in
the body. Sometimes these antibodies make an error and mistakenly recognize
normal proteins in our bodies as being foreign. Antinuclear antibodies
are autoantibodies -- antibodies that target the normal proteins within
the nucleus of a cell. This becomes clinically significant when ANAs signal
the body to begin targeting itself, which can lead to autoimmune diseases,
including lupus, Sjogren’s syndrome, and mixed connective tissue
disease. Clinical features that can emerge include but are not limited
to fever, chills, joint swelling, nasal/oral ulcers, hair loss, severe
dry eyes/dry mouth, and kidney disease. By itself, a positive ANA does
not in any way mean you have an autoimmune disease or need treatment.
It simply means that there are autoantibodies present. Without clinical
features or lab abnormalities such as leukopenia (low white blood cell
count), thrombocytopenia (low platelet count) or protein in the urine,
a positive ANA means exactly that. You simply have a positive lab test
without any features of an autoimmune disease.
How do you test for antinuclear antibodies? It’s simply a blood test,
but it should only be checked if you begin having any of the symptoms
mentioned above. Only about 10-13% of persons with a positive ANA test
are found to have lupus, and up to 15% of completely healthy people have
a positive ANA test without an autoimmune disease. The production of these
autoantibodies is strongly age-dependent and increases to 35% in healthy
individuals over the age of 65. Causes of a false-positive ANA include
infection, malignancy, and certain medications. Therefore, a positive
ANA test does not equal a diagnosis of lupus or any autoimmune or connective
When I have a patient with a positive ANA, it means I will need to order
more blood tests and take a detailed history of their symptoms as well
perform a detailed physical exam. Remember, a positive ANA does not equal
an autoimmune disease. But also remember that if it is determined that
you do have an autoimmune disease, there are treatment options for it.
So if you have a positive ANA, don’t panic. The next step is to see
a rheumatologist who will determine if additional testing is needed and
who will make sure you will get the best care for your particular situation.