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Arthritis and Rheumatism

ENA test vs ANA test

02/06/2007

Question:

Please discuss the difference between an ANA test and an ENA test. My ANA blood test came back positive, with Fin Spec, and now the doctor wants to do and ENA test. What is that?

Answer:

ANA is an acronym for Anti-Nuclear Antibody. Its use in Rheumatology is to screen for Connective Tissue Diseases; however, the presence of an ANA is not isolated to rheumatic diseases. The ANA is elevated by detecting antigens within the nucleus of a certain type of cell (most commonly, a Human Epithelial, type 2 cell (HEp-2)). However, the specific antigen within the nucleus that causes the elevation of the ANA is not known with the ANA test alone.

The ENA panel is an acronym for Extractable Nuclear Antigens. The ENA panel detects specific antigens within the nucleus that might be responsible for the elevated ANA. By knowing the specific antigen that is elevated, your physician may be able to better interpret your clinical data to arrive at a diagnosis.

Of note, it is not uncommon to have an elevated ANA and normal ENA panel. Also of note, the components of an ENA panel may vary between laboratory to laboratory.

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Response by:

Raymond  Hong, MD, MBA, FACR Raymond Hong, MD, MBA, FACR
Formerly, Assistant Professor of Medicine
School of Medicine
Case Western Reserve University