Labwork (blood testing) is a key component in diagnosing Sjögren’s Disease. When it comes to bloodwork, the antinuclear antibody (ANA) test is used as a primary test to help evaluate a person for autoimmune diseases. It’s a good place to start if Sjögren’s Disease is suspected. Most people think of Lupus (SLE) when they hear “ANA” but ANA is a group of autoantibodies produced by a person’s immune system when it fails to adequately distinguish between “self” and “nonself.” It can signify several different autoimmune disorders.
To distinguish further what an elevated ANA may mean for a person, further antibody testing can be completed. Two subsets of ANA: Anti-SS-A (Ro) and Anti-SS-B (La) are useful for identifying Sjogren’s. About 90% or more of people with Sjögren Disease have autoantibodies to SSA.The thing about these blood antibody tests, however, is that they can be positive in people with no known autoimmune disease or symptoms and they can also be positive in other autoimmune conditions besides Sjögren’s. On the other end of the spectrum, all of these lab tests can be negative in someone that does have Sjogren’s. So having them doesn’t necessarily mean you have (or don’t have) Sjögren’s Disease. While the lab work is highly suggestive of Sjögren’s, it is therefore not alone diagnostic.
Other non-specific bloodwork tests such as an ESR (Erythrocyte Sedimentation Rate) or CRP (C-Reactive Protein) are useful to identify inflammation that occurs with autoimmune disorders but they don’t distinguish where the inflammation is coming from or the cause of the inflammation.
RF (Rheumatoid Factor) is a lab test usually used to identify Rheumatoid arthritis but it can also be positive with Sjögren’s Disease. Rheumatic conditions share a lot of overlap symptoms and lab work. This makes it very hard to pinpoint exactly what is going on sometimes. However, all of this lab work is used to help form a bigger picture that hopefully can lead to a diagnosis.
If you have been following this blog post series on Diagnosing Sjögren’s Disease you may remember that my journey to diagnosis started with a finding of Leukopenia (low white blood cell count) on my lab work. Leukopenia can, of course, signify a barrage of different things but an autoimmune disease like Sjögren’s is one possible cause.
So in summary, the bloodwork most suggestive for a diagnosis of Sjögren’s Disease include a positive ANA with subtypes anti-SSA (Ro) and anti-SSB (La) antibodies. Additionally, RF may be positive. Alternatively, a biopsy of salivary glands from the lip showing a characteristic pattern of inflammation can be used for diagnosis. I will discuss this in my next blog post as I wrap up this series!
But wait. How do you diagnose dry mouth in Sjogren’s Disease?
How do you diagnose dry eye in Sjogren’s Disease?
When should you suspect Sjogren’s Disease?
Click here to see how my journey to diagnosis Sjogren’s began.