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; syphilis; systemic 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 on ICE
Same Day (Monday to Friday)
Serum in yellow top (SST) tube
Causes for Rejection
Not meeting specific criteria for analysis.
Less than 14 u/mL
RF may be raised in healthy patients over 60 years of age