ENA screen

The expected result is Negative. A positive screen is followed by a list of which of the individual antibodies (Ro, La, Sm, RNP, Scl-70, Jo-1, centromere and others) are present; some laboratories print a level for each.

The ENA screen looks for a group of antibodies directed against particular proteins inside the nucleus of the body's own cells, the extractable nuclear antigens. Each of the antibodies in the group is linked with a particular autoimmune condition, so when the screen is positive the laboratory reports which ones were found. It is usually run after a positive antinuclear antibody test.

Doctors request it, usually following a positive antinuclear antibody result, when looking at conditions such as lupus, Sjogren's syndrome, scleroderma, mixed connective tissue disease and some kinds of muscle inflammation.

• Sjogren's syndrome (Ro and La antibodies)
• Lupus (Sm, RNP and Ro antibodies)
• Scleroderma (Scl-70 and centromere antibodies)
• Mixed connective tissue disease (RNP antibodies)
• Some kinds of muscle inflammation (Jo-1 antibodies)

• Negative is the usual finding in healthy adults
• Once present, these antibodies usually persist and are not followed over time
• Immune-suppressing medicines rarely make them disappear

• A low-level positive, particularly Ro, is found in a small number of healthy adults
• Methods differ between laboratories, and a weak positive on one method may be negative on another

No fasting needed. A single result is read together with the antinuclear antibody result and the clinical picture; it is not usually repeated once the answer is known.

Written by a UK consultant physician. Typical UK adult reference ranges; your laboratory's own printed range takes precedence.