The Rheumatoid Factor (RF) test is a blood test that measures the level of rheumatoid factor, an autoantibody (a protein made by the immune system) that can mistakenly target the body’s own tissues. RF is often associated with rheumatoid arthritis, which is why some people refer to it as an “rf factor” test or “rheuma test.”

Results are typically reported as a number (titer or concentration). In general:

Higher-than-normal RF levels may support a diagnosis of rheumatoid arthritis or another autoimmune/inflammatory condition—but RF is not specific to RA. Some healthy people can have a positive RF, and RF can also rise with age, infections, or other immune conditions.

Normal (negative) RF does not rule out rheumatoid arthritis. Some people have seronegative RA (RA with a negative RF). Because of this, doctors often interpret RF alongside your symptoms, physical exam, imaging, and other labs (commonly anti-CCP antibodies, ESR, and CRP).

A clinician may order an RF test when symptoms suggest an autoimmune joint disease—especially rheumatoid arthritis—or when there is unexplained, ongoing inflammation. It is also used to help evaluate other autoimmune disorders and, in some cases, to estimate the likelihood of more aggressive disease when RA is suspected.

This test is commonly ordered if you have:

Joint symptoms lasting weeks to months—particularly pain, swelling, warmth, and morning stiffness (often >30–60 minutes), especially in the small joints of the hands and feet.

Symmetrical joint problems—for example, both wrists or both hands affected in a similar pattern.

Reduced function—difficulty gripping, opening jars, walking, or performing daily tasks due to joint discomfort or stiffness.

Systemic symptoms that can occur with inflammatory disease, such as fatigue, low-grade fever, unintentional weight loss, or generalized body aches.

Signs of autoimmune disease beyond joints—dry eyes/mouth, rashes, numbness/tingling, persistent cough/shortness of breath, or unexplained nodules—depending on the clinical picture.

RF testing may also be used for baseline assessment and to help guide next steps (such as additional antibody tests or referral to a rheumatologist). In established RA, RF positivity can be associated with a higher risk of certain complications, but the result alone does not determine your treatment plan.

• Rheumatoid arthritis (RA)
• Sjögren’s syndrome
• Systemic lupus erythematosus (SLE)
• Mixed connective tissue disease
• Systemic sclerosis (scleroderma)
• Chronic infections that can elevate RF (e.g., hepatitis C, endocarditis)
• Cryoglobulinemia (often associated with hepatitis C)
• Other inflammatory/autoimmune arthritides (less commonly)

• Earlier detection and evaluation of inflammatory arthritis symptoms (supporting timely treatment to protect joints)
• Clarifying whether joint pain is more likely autoimmune/inflammatory versus non-inflammatory (e.g., osteoarthritis)
• Guiding next-step testing (such as anti-CCP, ESR, CRP) and specialist referral for a complete rheumatology workup
• Risk stratification in suspected or confirmed rheumatoid arthritis (when interpreted with clinical findings)
• Supporting evaluation of systemic autoimmune symptoms (dry eyes/mouth, fatigue, rashes) in a broader diagnostic plan