Extractable Nuclear Antigen (ENA) Panel
The Extractable Nuclear Antigen (ENA) panel is a blood test used to diagnose and monitor autoimmune disorders, particularly those that affect the connective tissue. The test measures the levels of specific antibodies in the blood that are associated with these conditions.
What are ENAs?
ENAs are proteins found in the nucleus of cells that can trigger an immune response in certain individuals. When the body produces antibodies against these proteins, it can lead to inflammation and tissue damage, characteristic of autoimmune diseases such as lupus, scleroderma, and rheumatoid arthritis.
Components of the ENA Panel
A typical ENA panel includes tests for the following antibodies:
- Sm (Smith) antibody: highly specific for systemic lupus erythematosus (SLE)
- RNP (Ribonucleoprotein) antibody: associated with mixed connective tissue disease and SLE
- SS-A (Ro) antibody: found in Sjögren's syndrome and SLE
- SS-B (La) antibody: also associated with Sjögren's syndrome and SLE
- Scl-70 (Topoisomerase I) antibody: specific for scleroderma
- Jo-1 antibody: associated with polymyositis and dermatomyositis
How is the ENA Panel Performed?
The ENA panel is performed on a blood sample, which is sent to a laboratory for analysis. The test uses a technique called immunoblotting or enzyme-linked immunosorbent assay (ELISA) to detect the presence and levels of specific antibodies.
Interpretation of Results
The results of the ENA panel are interpreted in conjunction with clinical symptoms, medical history, and other laboratory tests. A positive result for one or more of the antibodies tested may indicate an autoimmune disorder, but it is essential to consider the overall clinical picture to make a definitive diagnosis.
Clinical Significance
The ENA panel is a valuable tool in the diagnosis and management of autoimmune diseases. It can help:
- Confirm a diagnosis of an autoimmune disorder
- Monitor disease activity and response to treatment
- Distinguish between different autoimmune conditions with similar symptoms
Article last updated on: 6th June 2025.
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