What is an SSB Blood Test?
Has your doctor recently scheduled you for an SSB blood test? If so, you may be confused as to what this test is and why it was ordered. An SSB test is a blood test that looks for specific antibodies in the blood stream called extractable nuclear antigens, or ENAs. Doctors often order this test along with another antibody test called an SSA blood test. The combination of these two blood tests provides valuable information that can help doctors diagnose certain autoimmune diseases.
Why is an SSB Blood Test Ordered?
As previously mentioned, an SSB blood test is ordered, along with an SSA test, to look for antibodies against extractable nuclear antigens, which are proteins found in the nucleus and the cytoplasm of cells. When these antibodies are present in the blood, it raises the possibility that a person has an autoimmune disease. Autoimmune diseases are diseases where the body produces antibodies against its own cells and tissues. This leads to tissue damage along with a variety of symptoms and complications.
When an SSB blood test is positive, it’s possible that a person has one of two autoimmune diseases, Sjogren’s syndrome or system lupus erythematosus, also known as SLE. Less commonly, an SSB blood test will be positive when a person has progressive systemic sclerosis or scleroderma.
SSB Blood Test and Sjogren’s Syndrome
Sjogren’s Syndrome is an autoimmune disease where antibodies are produced against the glands that produce tears and saliva. A person with this disorder will usually have a dry mouth and dry eyes - among other symptoms. If a person has Sjogren’s syndrome, an SSB blood test will be positive 60% of the time. The SSA blood test may also be positive in people who have this disorder, but it’s a less specific test that can be abnormal in a variety of other conditions.
Sometimes other antibody tests are used along with the SSA and SSB blood test to help make the diagnosis of Sjogren’s but the final diagnosis is made based on clinical findings along with antibody testing.
The SSB Test, SLE and Other Conditions
An SSB blood test is positive in 15-25% of people with SLE, but it’s only one of several antibody tests doctors use to evaluate this common autoimmune disease. Again, the clinical picture is important for making the diagnosis, along with lab tests, since a positive SSB test isn’t specific for any one disease. It will also be positive in 5-10% of people with progressive systemic sclerosis, a disease that causes hardening of collagen and can affect blood vessels as well as internal organs.
The Bottom Line
The SSB blood test provides valuable information needed for making the diagnosis of certain autoimmune diseases - when used in conjunction with a thorough clinical exam and other lab studies. A positive SSB test isn’t specific for a single disease, but it’s most likely to be positive in people who have Sjogren’s syndrome or SLE.
ARUP Lab Tests. “Extractable Nuclear Antigen Antibodies”
Mayo Clinic. “SSA and SSB Antibodies