Norm of Anti-Ro/SS-A Test
Negative or <20 units.
ANA-negative lupus, complete congenital heart block, neonatal lupus, polymyositis/dermatomyositis, and Sjögren's syndrome.
Description of Anti-Ro/SS-A Test
Anti-Ro/SS-A is an autoantibody to the cytoplasmic RNA Ro antigen characteristically found in high titers in clients with primary Sjögren's syndrome or Sjögren's syndrome with systemic lupus erythematosus (SLE). Although electrophoresis is the most sensitive testing method for detection of these antibodies, the most common method used is immunodiffusion. This test is used in the differential diagnosis of SLE, Sjögren's syndrome, and mixed connective tissue disease. The antibody is present in over 70% of Sjögren's syndrome, 30%–40% of SLE, and only 5%–10% of progressive systemic sclerosis.
Professional Considerations of Anti-Ro/SS-A Test
Consent form NOT required.
Tube: Red topped, red/gray topped, or gold topped.
Draw a 4-mL blood sample.
Send the specimen to the laboratory for immediate spinning.
Client and Family Teaching
Results may not be available for several days if testing is not performed on site.
Factors That Affect Results
Reject lipemic, hemolyzed, or contaminated specimens.
- This test is more sensitive but less specific for primary Sjögren's syndrome than the anti-La/SS-B test.
- The presence of both anti-La/SS-B and anti-Ro/SS-A antibodies is generally associated with a milder form of SLE.
- Clients who are positive for antinuclear antibody and who have SS-A, but not SS-B, are likely to have nephritis.
- African-Americans are at increased risk for the presence of anti-Ro antibodies and SLE.