12/10/2016
ANA ( Antinuclear Antibody )
How is it used?
The antinuclear antibody (ANA) test is used as a primary test to help evaluate a person for autoimmune disorders that affect many tissues and organs throughout the body (systemic) and is most often used as one of the tests to help diagnose systemic lupus erythematosus (SLE).
ANA are a group of autoantibodies produced by a person's immune system when it fails to adequately distinguish between "self" and "nonself." They target substances found in the nucleus of a cell and cause organ and tissue damage.
When is it ordered?
The ANA test is ordered when someone shows signs and symptoms that are associated with a systemic autoimmune disorder. People with autoimmune disorders can have a variety of symptoms that are vague and non-specific and that change over time, progressively worsen, or alternate between periods of flare ups and remissions. Some examples of signs and symptoms include:
-Low-grade fever
-Persistent fatigue, weakness
-Arthritis-like pain in one or more joints
-Red rash (for lupus, one resembling a butterfly across the nose and cheeks)
-Skin sensitivity to light
-Hair loss
-Muscle pain
-Numbness or tingling in the hands or feet
-Inflammation and damage to organs and tissues, including the kidneys, lungs, heart, lining of the heart, central nervous system, and blood vessels.
What does the test result mean?
A positive ANA test result means that autoantibodies are present. In a person with signs and symptoms, this suggests the presence of an autoimmune disease, but further evaluation is required to assist in making a final diagnosis.
Tests for ANA:
Amount of autoantibody present....
Two types of tests are commonly performed to detect and measure ANA:
1. Immunoassay (enzyme linked immunosorbent assay, ELISA, or enzyme immunoassay, EIA)—the results are usually reported as a number with an arbitrary unit of measure (abbreviated as a "U" on the report, for example).
2. Indirect fluorescent antibody (IFA)—the results of this method are reported as a titer. Titers are expressed as ratios. For example, the result 1:320 means that one part blood sample was mixed with 320 parts of a diluting substance and ANA was still detectable.