19 Dec Rheumatoid factor
Alternative Names: RF
A blood test that measures RF (rheumatoid factor) — a type of antibody that is produced by the immune system — is done when considering autoimmune conditions. These conditions, in which the body’s immune system seems to attack its own tissues and organs, include rheumatoid arthritis, systemic lupus erythematosus (SLE), and scleroderma. Viral infections and inflammation of the liver (hepatitis) can also cause positive RF results. A blood sample is withdrawn, through a needle, usually from a vein inside the elbow, and sent for laboratory analysis.
What is it?
Rheumatoid factor refers to a blood test that measures rheumatoid factor (RF), which is a type of antibody (a substance produced by the immune system).
The taking of the blood sample can be done at any doctor’s rooms or clinic – the analysis is done in a laboratory.
Why is it done?
The RF blood test is done when considering autoimmune diagnoses (conditions where the body’s immune system seems to attack its own tissues and organs) such as:
- Rheumatoid arthritis
- Systemic lupus erythematosus (SLE)
A positive result is, however, rarely conclusive, because other conditions like viral infections and hepatitis (inflammation of the liver) can also cause positive RF results. Further tests are often required.
Before – how to prepare
No special preparation is necessary.
During – how the test is done
A convenient area, where there are prominent veins, is identified and cleaned – the area inside the elbow is often used. A tourniquet or tight band is applied above the area in order to increase pressure and dilate the veins. A needle is then inserted, through the skin, into a vein, and some blood is withdrawn. The needle may cause some pain but this is not usually severe. The blood specimen is sent to the laboratory for analysis.
After the test
You will have a small dressing over the puncture wound, which can be removed after a few hours.
Risks and Compilations
There is a slight risk of excessive bleeding at the puncture site and an even smaller risk of infection.
A blood test that measures RF (rheumatoid factor) — a type of antibody that is produced by the immune system — is done when considering autoimmune conditions.
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