This is a simple blood test that measures rheumatoid factor, an antibody that, if it is present, will help your doctor know if you have rheumatoid arthritis. Your body produces antibodies when it detects harmful substances.
High levels of rheumatoid factor can show up in people with severe rheumatoid arthritis. But even if the test results show you have a high level of it, your doctor will want to do other tests before they make a diagnosis. They will also examine you and may order other types of lab tests, such as X-rays, an MRI, an ultrasound, or other scans.
How Is It Done?
You won’t have to do anything to prepare. Some people are more sensitive than others about having blood taken. If you have questions, talk to your doctor before the test. If you feel faint or nauseated, let your doctor know.
Remember, sometimes the rheumatoid factor is also found in the blood of healthy people. And it’s found in people with other immune system conditions like lupus and Sjogren's syndrome. People with chronic infections like viral hepatitis can have it too.