Rheumatoid factor (RF) testing is an essential tool for diagnosing autoimmune disorders like rheumatoid arthritis. By detecting specific antibodies in the blood, this test helps to identify inflammatory conditions and assess their severity, while guiding the appropriate treatment for the patients concerned.
A rheumatoid factor (RF) test looks for rheumatoid factor (RF) in a sample of your blood. Rheumatoid factors are proteins that are produced by the immune system.
Normally, your immune system produces proteins called antibodies to attack germs that could make you sick. But rheumatoid factors are antibodies that sometimes mistakenly attack healthy cells and tissues in your body. When that happens, you have an autoimmune disorder.
Not everyone has rheumatoid factors in their blood. And some people who have them are healthy. But if you have certain symptoms and higher levels of rheumatoid factors, you could have an autoimmune disorder or other health condition that is linked to high levels of RF.
The RF test is primarily used with other tests to help diagnose rheumatoid arthritis. Rheumatoid arthritis (RA) is a type of autoimmune disorder that damages your joints and causes pain, swelling, and stiffness. It is a chronic (long-lasting) condition that can also affect your organs and cause other symptoms.
High levels of rheumatoid factors can also be a sign of other autoimmune disorders, certain infections, and certain types of cancer.
Other names: RF blood test
An RF test is often used to help diagnose rheumatoid arthritis and other autoimmune disorders. The RF test can also be used to understand the severity of rheumatoid arthritis and whether it is likely to affect organs. An RF test alone cannot diagnose health problems.
You may need an RF test if you have symptoms of rheumatoid arthritis. Symptoms often start in the wrists, hands, and feet. They generally affect the same joints on both sides of the body and tend to come and go.
Symptoms of rheumatoid arthritis may include:
You may also need an RF test if you are taking tests to diagnose another condition that may cause high levels of rheumatoid factor, such as:
A health professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected in a test tube or vial. You may feel a slight prick when the needle goes in or out. This usually takes less than five minutes.
Home tests for rheumatoid factor are available. The test kit provides everything you need to take a blood sample by pricking your finger. You will send your sample to a laboratory for analysis. If you're doing a home test, it's important to share your results with your healthcare professional.
You don't need any special preparations for an RF test.
There is very little risk in taking a blood test. You may feel a slight pain or bruise where the needle was inserted, but most symptoms go away quickly.
An RF test alone cannot diagnose conditions. To make a diagnosis, your provider will review the results of other tests as well as your symptoms and medical history.
A negative result (normal) means you have little or no rheumatoid factor in your blood. But that doesn't rule out rheumatoid arthritis or another health condition. Many people with rheumatoid arthritis have little or no rheumatoid factor. If you have symptoms of rheumatoid arthritis but your RF test results are normal, your provider may order additional tests to make a diagnosis.
A positive (abnormal) result means that a higher level of rheumatoid factor has been found in your blood. This doesn't always mean rheumatoid factors are causing your symptoms. But the higher your RF test scores, the more likely it is that you have a condition linked to rheumatoid factors. Your provider can do further tests to determine if you have:
Learn more about lab tests, reference ranges, and understanding results.
An RF test is not steps used to diagnose osteoarthritis. Although rheumatoid arthritis and osteoarthritis both affect joints, they are very different diseases. Arthrosis is not steps an autoimmune disease and does not involve the rheumatoid factor. Researchers are not sure what causes osteoarthritis. It mainly affects the elderly.
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