Author: Jill Silverman, MD
As an arthritis and autoimmune disease specialist, or rheumatologist, I frequently see patients who fear that they have lupus. Lupus is one of many "autoimmune diseases". In these conditions, a patient's immune system attacks her own cells and tissues. This can result in problems such as arthritis and skin rashes, or more seriously, kidney, heart, brain or lung disease. Blood tests can identify a marker of lupus called the antinuclear antibody, or ANA. This blood test checks for the presence of certain antibodies in the blood that react against the proteins of the patient's own cells, particularly those in the nucleus (hence the name of the test). In many of the cases I see, the patient has recently had a blood test that reveals a positive antinuclear antibody (ANA). These results in hand, she arrives at her appointment sure she has lupus.
In a recent case, for instance, I saw a thirty six year old patient named Ana. Ana had gone to her primary doctor complaining of fatigue and joint pain. The doctor performed a series of blood tests, including one to check thyroid levels, another to check for anemia, and an ANA to check for autoimmune diseases. There are many autoimmune disease which can cause arthritis and fatigue. Because they cause a state of generalized inflammation, and inflammation is exhausting to the body, someone with an active autoimmune disease is often tired. Lupus is one of these disorders and it is also especially common in young women. Ana’s doctor performed an ANA test, and it was positive. Ana then googled " positive ANA" and was quickly presented with the diagnosis of lupus. (Google really isn't a very good doctor). By the time she arrived in my office, she was terrified that she had a potentially life-threatening, chronic disease.
What's wrong with this picture?
First, the most common causes of fatigue and joint aching are not autoimmune conditions such as lupus. Most of the time, I find that these symptoms are related to lifestyle factors, like stress, lack of exercise, and poor sleep habits, or psychological factors, like anxiety, depression or PTSD. Lupus is a disease with significant clinical or laboratory findings that are easily discernible on exam or on the lab reports. It's not just joint pain that is present in patients with lupus. It is joint pain, swelling, redness and limited motion. It's not just a positive ANA, but multiple other laboratory abnormalities, including low white blood cell counts, anemia, low platelets, and protein in the urine. And although fatigue is a feature of this disease, this symptom alone rarely brings a lupus patient to the physician.
In addition, the ANA is a particularly unreliable test. Ten to fifteen percent of adults with no evidence of disease have a positive ANA. This means that there are more healthy people with positive ANAs out there than lupus patients with the same. This has certainly been my experience as a rheumatologist. I see many more patients with positive ANAs that don't have any autoimmune diseases than I see lupus patients. In addition, depending on how the test is performed, it may be positive in one lab and negative in another. When I see a healthy patient referred to me with a positive ANA, I usually repeat the test, and it often comes back negative.
In other words, a positive ANA test is necessary but not sufficient to make the diagnosis of lupus. Fatigue, joint aching and a positive ANA without other physical findings like joint swelling, certain specific rashes, abnormal blood counts or urinalysis
rarely add up to an autoimmune diagnosis. A rheumatologist can help you sort through all this, but while you wait for an appointment: don't panic.