The ENA (extractable nuclear antigen) panel is a blood test that looks for antibodies to 6 or 7 different proteins in the body. These antibodies include:
- anti-Ro (also called anti-SSA)
- anti-La (also called anti-SSB)
- anti-Sm (anti-Smith antibody)
- anti-RNP (anti-ribonucleoprotein)
These are types of autoantibodies: antibodies that are produced by the immune system that target something the body’s own tissues are made of. The ENA panel is usually ordered as a follow-up after a positive ANA (anti-nuclear antibody) test in a person who has signs and symptoms of an autoimmune disease.
The ENA panel may be ordered to help make a diagnosis of the following autoimmune disorders:
- Systemic Lupus Erythematosus (SLE)
- Mixed connective tissue disease (MCTD)
- Sjögren’s syndrome
The results of the ENA panel can be difficult to interpret. It’s best to discuss this with your rheumatologist.