Rheumatoid factor (RF) is an autoantibody that attacks healthy tissue, particularly in the joints. It is most commonly used to help diagnose rheumatoid arthritis.
Category: Inflammation & Immune
Also known as: rheumatoid factor, rf, ra factor, rheumatoid factor quantitative
Reference range: 0–14 IU/mL (Source: ABIM)
Standard unit: IU/mL
High values may indicate
High rheumatoid factor levels may indicate rheumatoid arthritis, Sjogren's syndrome, systemic lupus erythematosus, chronic infections (hepatitis C, tuberculosis), or other autoimmune disorders.
Low values may indicate
Low or negative rheumatoid factor levels are normal. However, some people with rheumatoid arthritis may have negative RF (seronegative RA).