Systemic Lupus Erythematosus (lupus) has historically been called "the great imitator" within diseases. And mind you, lupus has earned this title fair and square because it, as many of you know, can affect many different systems of the body which can cause an incredibly varied array of signs and symptoms. (That's a mouthful!) The screening test for lupus is the antinuclear antibody blood test (ANA) and it's incredibly rare that someone with lupus would have a negative ANA. However, having a positive ANA does not necessarily mean that you do have lupus. Pretty confusing? You betcha.
However, there are numerous medical conditions that are characterized by pain and fatigue which can cause sufficient stress to confuse the immune system into making an auto-antibody like ANA, albeit in small amounts - certainly too small to cause obvious disease. Most of these patients had something else and it took a great deal of time, energy and further testing in an effort to explain and to convince them that they did not have lupus - they were just that convinced that they did - and who could blame them? Getting a positive ANA is just plain scary. Furthermore, what added stress to the patient believing that lupus was hanging over the their head until the patient's condition was indeed straightened out!
And so the important point to remember is that the ANA is not just a test that is positive or negative. There are DEGREES of positivity. (Please keep in mind that this is all common knowledge in the rheumatology world.)
The way the test results are reported is in the manner of a ratio which represents how strong the antibody concentration is in the serum (blood without the cells). For example, an ANA that is positive at a titer of 1:40 is a rather low amount of ANA, which is often found in patients with a variety of diseases, including fibromyalgia. On the other hand, an ANA with a titer of 1:1,280 is a high titer, one that's often seen in lupus patients.
Keep in mind that the pattern of ANA is also important. There are four different patterns that can be seen under the microscope: homogeneous, speckled, nucleolar and peripheral. The latter, peripheral, is more consistent with lupus than the others.
If a patient has a high titer ANA, further studies are typically done to nail down the correct diagnosis. These often include a double-stranded DNA test and serum complement levels. Of course, a good physical examination is essential in pointing the way to the most critical blood test to be drawn in order to differentiate among the likely diagnosis in order to come to a correct diagnosis.
The bottom line is that a patient might have a positive ANA but that does not necessarily mean that one is dealing with lupus. It takes a skilled clinician to determine if lupus is present or not, and if not, what is causing the patient's symptoms along with the positive ANA.
True, lupus IS "the great imitator" but problems such as fibromyalgia and early rheumatoid arthritis (both of which can have positive ANA's) are up-and coming contenders for that title. How many of you have had low titer positive ANA's, or worried that you might have lupus and it turned out to be something else? Worse, the positive ANA was not explained at all, or just poo-pooed?
I hope this helps shed some light on an area that can be very confusing and worrisome.
In the meanwhile, I hope everyone out there is feeling their best - only better! Ciao and paka.
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