The Lupus-specific tests may indicate that you do not have Lupus, but may have another auto-immune disorder. However, despite the fact that a positive anti-Sm antibody test will confirm lupus, a negative test does not eliminate Lupus. However, most lupus patients have either a positive anti-DNA or positive anti-Sm antibody test. In most cases, a negative test for both means that the patient does not have lupus. Anti-DNA is an immunoglobulin specific against native (double-stranded) DNA. It is increased in Systemic lupus erythematosus & is highly specific to SLE.
Sixty to eighty percent of people with active Lupus have a positive anti-DNA test. However, only 10 percent of lupus patients have a positive anti-Sm test, but 90 percent of people who have positive Sm tests have lupus. I know, it's maddening and confusing, but that is the nature of the disease :? But, as I mentioned above, having a negative result for both tests usually indicates that you do not have Lupus, but that you may have another auto-immune disorder.
There are so many other disorders in this category that have symptoms resembling Lupus symptoms. In light of your positive ANA, it is possible that you may have one of these other auto-immune diseases. A positive ANA can be found in:
* Sjögren’s syndrome: Between 40% and 70% of patients with this condition have a positive ANA test result. While this finding supports the diagnosis, a negative result does not rule it out. The doctor may want to test for two subsets of ANA: Anti-SS-A (Ro) and Anti-SS-B (La). The frequency of autoantibodies to SSA in patients with Sjögren’s can be 90% or greater.
* Scleroderma: About 60% to 90% of patients with scleroderma have a positive ANA finding. In patients who may have this condition, ANA subset tests can help distinguished two forms of the disease, limited versus diffuse. The diffuse form is more severe. Limited disease is most closely associated with the anticentromere pattern of ANA staining (and the anticentromere test), while the diffuse form is associated with autoantibodies to the anti–Scl-70.
* A positive result on the ANA also may show up in patients with Raynaud’s disease, rheumatoid arthritis, dermatomyositis, mixed connective tissue disease, and other autoimmune conditions.
You doctors will probably want to do additional testing in order to determine which, if any, auto-immune disorder you might have.
Peace and Blessings