Pathology Handbook

Rheumatoid factor

Synonyms

RF

Clinical Indications

The rheumatoid factor (RF) test is used to help diagnose RA and to distinguish it from other forms of arthritis and other conditions that cause similar symptoms of joint pain, inflammation, and stiffness. It may be requested with other autoimmune related tests, such as ANA (antinuclear antibody), markers of inflammation, such as CRP (C-reactive protein) and ESR(erythrocyte sedimentation rate), and with FBC (Full Blood Count) to evaluate the body's blood cells.

Cyclic Citrullinated Peptide Antibody (CCP) is a relatively new test that can help detect early RA may be used if RF is negative, and there is a high suspicion of RA. The RF test may also be requested with other autoantibody tests such as anti-Ro (SS-A) and anti-La (SS-B) which help diagnose Sjögren's  syndrome.

A negative RF test does not exclude RA or Sjögren's syndrome. About 20% of patients with RA or Sjögren's syndrome will be persistently negative or have low levels of RF.

Positive RF test results may also be seen in healthy patients and in patients with conditions such as: infections; viral infection; endocarditis; tuberculosis; syphilissystemic lupus erythematosus (lupus); sarcoidosis; cancer; or disease of the liver, lung, or kidney. The RF test is not used to diagnose or monitor these conditions.

Request Form 

Request on ICE

Availability

On request

Specific Criteria

None

Patient Preparation

None 

Turnaround Time

Same Day (Monday to Friday)

Specimen

Serum in yellow top (SST) tube

Volume

2 mL

Container

Vacutainer gold top

Collection

-

Causes for Rejection

Unlabelled sample
Not meeting specific criteria for analysis. 

Reference Range

Less than 14 u/mL

RF may be raised in healthy patients over 60 years of age