Extractable nuclear antigen antibody panel (ENA)

What it measures

Tests for antibodies to specific nuclear antigens such as Sm, RNP, Ro/SSA, La/SSB, Scl-70 and Jo-1. It identifies the particular connective tissue disease after a positive ANA.

Specimen and preparation

• Specimen: Serum
• Tube: Gold top

Reference range

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

• Anti-Sm: SLE (specific)
• Anti-U1 RNP: mixed connective tissue disease
• Anti-Ro/La: Sjögren, neonatal lupus, congenital heart block
• Anti-Scl-70: diffuse systemic sclerosis
• Anti-Jo-1: antisynthetase syndrome/polymyositis

Method

Line immunoassay, ELISA, CLIA or multiplex bead assay

Good to know

Anti-centromere (limited scleroderma) is usually seen on ANA pattern or included in extended panels.

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