ENA Antibodies Test (Extractable Nuclear Antigens)

The ENA Antibodies Test (Extractable Nuclear Antigens) is a specialised blood test used to detect autoantibodies directed against a group of soluble nuclear and cytoplasmic proteins. These antibodies are important markers in the investigation of systemic autoimmune rheumatic diseases, including systemic lupus erythematosus (SLE), Sjögren's syndrome, systemic sclerosis (scleroderma), mixed connective tissue disease (MCTD), and polymyositis/dermatomyositis. This test is typically requested when a patient has persistent symptoms such as joint pain, unexplained rashes, Raynaud's phenomenon, dry eyes and mouth, muscle weakness, or when a positive antinuclear antibody (ANA) result requires further clarification. It is also used to monitor disease activity and assist in distinguishing between different autoimmune conditions.

The test is performed using a validated immunoassay technique, most commonly enzyme-linked immunosorbent assay (ELISA) or a multiplex flow immunoassay, to screen for specific ENA antibodies. A simple blood sample is collected by a trained phlebotomist.

Markers typically included in the ENA panel

• Anti-nuclear antibodies (ANA) - often screened first, but ENA panel focuses on specific subtypes
• Anti-double-stranded DNA (anti-dsDNA) - associated with SLE and lupus nephritis
• Anti-Smith (anti-Sm) - highly specific for SLE
• Anti-Ro (SS-A) and anti-La (SS-B) - linked to Sjögren's syndrome, subacute cutaneous lupus, and neonatal lupus
• Anti-U1 ribonucleoprotein (anti-U1 RNP) - associated with mixed connective tissue disease (MCTD) and overlap syndromes
• Anti-Scl-70 (anti-topoisomerase I) - associated with diffuse systemic sclerosis
• Anti-centromere - associated with limited cutaneous systemic sclerosis (CREST syndrome)
• Anti-Jo-1 (anti-histidyl-tRNA synthetase) - associated with polymyositis and interstitial lung disease
• Anti-ribosomal P - associated with lupus psychosis and severe SLE
• Anti-PM-Scl - associated with polymyositis/scleroderma overlap
• Anti-Mi-2 - associated with dermatomyositis

Why it matters
Identifying specific ENA antibodies helps clinicians differentiate between autoimmune conditions that can have overlapping symptoms but require different management strategies. Early and accurate diagnosis can guide appropriate treatment, reduce the risk of organ damage, and support clinical management. For patients, this test provides clarity and a clearer path toward targeted care.

Extractable Nuclear Antigens (ENA) Panel
- Anti-nuclear antibodies (ANA)
- Anti-double-stranded DNA (anti-dsDNA)
- Anti-Smith (anti-Sm)
- Anti-Ro (SS-A)
- Anti-La (SS-B)
- Anti-U1 ribonucleoprotein (anti-U1 RNP)
- Anti-Scl-70 (anti-topoisomerase I)
- Anti-centromere
- Anti-Jo-1 (anti-histidyl-tRNA synthetase)
- Anti-ribosomal P
- Anti-PM-Scl
- Anti-Mi-2

No special preparation required.

For blood tests, we recommend drinking plenty of water beforehand to ensure smooth sample collection. If you are taking any regular medication, continue to do so unless advised otherwise by your doctor.