Rheumatoid arthritis antinuclear antibodies 1:160
by Nathan Wei, MD, FACP, FACR
Nathan Wei is a nationally known board-certified rheumatologist and author of the Second Opinion Arthritis Treatment Kit. It's available exclusively at this website... not available in stores.
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Rheumatoid arthritis is the most common form of inflammatory arthritis. It affects about 1% of the population- almost two million Americans. The diagnosis is based upon history, physical examination, imaging procedures, and laboratory tests.
From the Arthritis Foundation
Since inflammatory arthritis is a feature of many autoimmune diseases, it is important to look at the complete clinical picture.
One of the laboratory blood tests that is often ordered is the ANA… or anti-nuclear antibody test.
Antinuclear antibodies are a group of autoantibodies that have the ability to attack structures in the nucleus of cells.
To perform the ANA (antinuclear antibody) test a blood sample is drawn from the patient and sent to the lab for testing.
Serum from the patient's blood specimen is added to slides which have commercially prepared cells on the slide surface. If the patient's serum contains antinuclear antibodies (ANA), they bind to the cells (specifically the nuclei of the cells) on the slide.
A second antibody, commercially tagged with a fluorescent dye, is added to the mix of patient's serum and commercially prepared cells on the slide. The second (fluorescent) antibody attaches to the serum antibodies and cells which have bound together. When viewed under an ultraviolet microscope, antinuclear antibodies appear as fluorescent cells.
• If fluorescent cells are observed, the ANA (antinuclear antibody) test is considered positive.
• If fluorescent cells are not observed, the ANA (antinuclear antibody) test is considered negative.
A titer is determined by repeating the positive test with serial dilutions until the test yields a negative result. The last dilution which yields a positive result (fluorescence) is the titer which gets reported. For example, if a titer performed for a positive ANA test is:
So, the test is reported as positive at a 1:160 titer.
An ANA report has three parts:
• positive or negative
• if positive, a titer is determined and reported
• the pattern of fluorescence is reported
ANA titers and patterns can vary between laboratory testing sites, perhaps because of variation in methodology used. These are the commonly recognized patterns:
• Homogeneous - total nuclear fluorescence due to antibody directed against nucleoprotein. Common in SLE (lupus).
• Peripheral - fluorescence occurs at edges of nucleus in a shaggy appearance. Anti-DNA antibodies cause this pattern.
• Speckled - results from antibody directed against different nuclear antigens.
• Nucleolar - results from antibody directed against a specific RNA configuration of the nucleolus. This pattern is seen in patients with systemic sclerosis (scleroderma).
ANAs are found in patients who have various autoimmune diseases, but not only autoimmune diseases. ANAs can be found also in patients with infections, cancer, lung diseases, gastrointestinal diseases, hormonal diseases, blood diseases, skin diseases, and in elderly people or people with a family history of rheumatic disease. ANAs are also found in about 5% of the normal population.
The ANA results are just one factor in diagnosing, and must be considered together with the patient's clinical symptoms and other diagnostic tests. Medical history also plays a role because some prescription drugs can cause "drug-induced ANAs".
The incidence of positive ANA (in percent) for various autoimmune conditions is:
• Systemic lupus erythematosus (lupus or SLE) - over 95%
• Progressive systemic sclerosis (scleroderma) - 60-90%
• Rheumatoid Arthritis - 25-30%
• Sjogren's syndrome - 40-70%
• Felty's syndrome - 100%
• Juvenile arthritis - 15-30%
The ANA (antinuclear antibody) test is complex, but the results (positive or negative, titer, pattern) and possible subset test results can give physicians valuable diagnostic information.
Occasionally patients with rheumatoid arthritis will also have clinical features that suggest an overlap syndrome with another autoimmune disease. These patients are sometimes diagnosed with “rhupus.”
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