One of the first tests that a doctor will order when a patient is suspected of having Lupus is an antinuclear test called the ANA.
That test studies serum (blood etc.) to see if there are any active autoantibodies doing battle with antigens.
There are two methods used to conduct this test, ELISA which is pretty much of an automated process, and the old fashion method called Immunofluorescent Assay. The old fashion technique involves an experienced lab technician to look for those little culprits under a sophisticated microscope.
The ELISA test is considered more sensitive and specific, and most importantly it is really quick and cheap to do.
There are two types of ELISA tests, quantitative and qualitative. The usual test that is ordered is the ‘quantitative’ which gives either a ‘positive’ or ‘negative’ result. A ‘qualitative’ test will actually list the ratio of any positive result. They both use the metric of ‘dilution’ to analyze the results.
Hence if your ELISA ANA test is negative, most doctors will stop there and suggest that you may have some other ailment in lieu of Lupus.
Unfortunately these tests are not perfect nor are they regulated per se by the FDA.
In fact, there are numerous manufacturers of ELISA Kits all vying for business with medical laboratories.
Each of the different manufacturers have their own design protocol for creating an ELISA Kit supplying the supposedly correct antigens to be used against a patient’s serum that may or may not contain autoantibodies. Remember, the goal is looking for too many autoantibodies which may be causing havoc in your body.
The American College of Rheumatology which is the pseudo-governing body of standards for rheumatic diseases recommends using the old fashion test, specifically the Indirect Immunofluorescent Assay (IIFA). They refer to it as “the gold standard.”
This test requires an experienced lab technician to analyze the patient’s autoantibodies against targeted antigens. The semi-automated ELISA test takes around 90 minutes and the IIFA test can take anywhere up to 3 hours to complete. Furthermore, most reputable labs using the IIFA will have at least three lab technicians verify the results before committing to them.
In a research paper published by the Cleveland Clinic in July of 2015, they concluded that although the ELISA test is more sensitive and specific, the IIFA test with a positive low titer ratio of 1:40 is what should be used in evaluating a patient for Lupus.
After careful analysis of varying ELISA Kits tested against a sample population of patients with a concrete diagnosis of Lupus, they discovered that the ELISA test could actually provide a false negative.
In other words, a higher sensitivity and specificity does not always provide an accurate result.
Furthermore, if one peruses the Lupus Support network and reads the comments by a multitude of individuals, many have reported that every six months their ANA test will revert to either a positive or a negative. The implication is that sometimes an ANA test is only relevant during an active disease state.
Should the reader of this post still be in the process of being evaluated for Lupus and an ANA test has been done, first check to see if it was an ELISA test, then whether or not it was a ‘quantified’ or ‘qualified’ test.
If it was an ELISA test and it came back negative, use the report referenced in this post with the link above and show it to your rheumatologist.
Ask your doctor to request an Indirect Immunofluorescent Assay (IIFA) test be conducted to see if there is a positive result at a dilution of 1:40.
In order for either the ELISA ANA test or the IIFA ANA test to be of value, it is essential that the patient is not currently taking any kind of immunosuppressant medications such as Prednisone or Aspirin.
[To be continued…]