What is the Rheumatoid Factor test?

The Rheumatoid Factor (RF) blood test measures antibodies that target the body’s own tissues, particularly within joints. Rheumatoid factor is most commonly associated with rheumatoid arthritis, a chronic autoimmune condition that causes joint inflammation, pain, and progressive damage.

RF may also be present in other autoimmune diseases, chronic infections, and inflammatory conditions. While not diagnostic on its own, RF testing is a key component in evaluating inflammatory joint disease.

This test is often interpreted alongside anti-CCP antibodies, inflammatory markers, and clinical findings.

Why do I need a test for Rheumatoid Factor?

Autoimmune joint conditions often begin subtly, with stiffness or joint pain appearing before clear swelling or deformity. Early testing helps identify immune-mediated inflammation and supports early specialist referral.

RF testing is especially useful when symptoms persist or when inflammatory arthritis is suspected.

You may benefit from this test if you experience:

• Persistent joint pain or swelling

• Morning stiffness lasting over an hour

• Symmetrical joint symptoms

• Fatigue or low-grade fever

• Reduced joint mobility

• Family history of autoimmune disease

• Suspected rheumatoid arthritis

• Monitoring inflammatory joint disease

Benefits of the Rheumatoid Factor test

1. Supports rheumatoid arthritis investigation
   One of the key markers used in RA assessment.

2. Identifies autoimmune joint inflammation
   Reflects immune-mediated tissue damage.

3. Helps guide early referral
   Supports timely rheumatology input.

4. Useful alongside anti-CCP antibodies
   Improves diagnostic confidence when combined.

5. Assesses systemic autoimmune activity
   RF may be elevated in other autoimmune diseases.

6. Supports disease monitoring
   Levels may correlate with disease severity.

7. Aids differential diagnosis
   Helps distinguish inflammatory from mechanical joint pain.

8. Simple blood-based autoimmune marker
   Requires only a routine blood sample.

Step-by-step – how we offer Rheumatoid Factor testing

Clinic-based testing (UK-wide)

• Choose your nearest UK clinic

• Attend your appointment

• Blood sample collected by a qualified clinician or phlebotomist

• Sample is sent to the laboratory for analysis

At-home or hotel testing (+£60)

• A qualified phlebotomist visits your home or hotel

• Blood sample collected in a comfortable, familiar setting

• No clinic visit or travel required

Both services are available UK-wide.

Your Rheumatoid Factor results explained

Negative Rheumatoid Factor

A negative RF result suggests no detectable rheumatoid factor. This makes rheumatoid arthritis less likely but does not completely exclude it, particularly in early disease.

Further testing may still be indicated based on symptoms.

UK reference interpretation:

• Negative: <14 IU/mL

Low-positive Rheumatoid Factor

Low-positive results may occur in early rheumatoid arthritis, other autoimmune conditions, chronic infections, or even in healthy individuals, especially with increasing age.

Clinical correlation is essential.

UK reference interpretation:

• Low positive: 14–50 IU/mL

High Rheumatoid Factor

High RF levels are more strongly associated with rheumatoid arthritis and may correlate with more severe or aggressive disease.

Further rheumatological assessment is often recommended.

UK reference interpretation:

• High: >50 IU/mL