Arthritis Health Center

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Blood that is very high in fats.
• Age. Some people older than age 65 have a high RF level.
• Having had multiple vaccinations or blood transfusions.

What To Think About

• A small number of people have a high RF level but do not have rheumatoid arthritis. A small number of these people will later have rheumatoid arthritis.
• A health professional always uses the results of an RF test along with information gained from a medical history and physical examination before diagnosing rheumatoid arthritis.
• Cyclic citrullinated peptide (CCP) is an antibody that is found in the blood of more than half of all people who have rheumatoid arthritis. It is used to confirm a diagnosis of rheumatoid arthritis.
• Older adults who do not have rheumatoid arthritis sometimes have a slightly high RF level.
• Some people have rheumatoid arthritis and have a normal level of RF. The RF test may need to be repeated if rheumatoid arthritis is suspected and the first RF level was normal.
• Less than one-third of children who have juvenile idiopathic arthritis have a high RF level.