What Is Rheumatoid Factor?

In simple words, rheumatoid factor (RF or RHf) is an antiobody which has been developed within the body and against its own tissues. Therefore, it can be called as an autoantibody.

It is mostly found in rhematoid arthritis patients. But those rheumatoid patients who do not show presence of RHf are called “seronegative”

How Does it Work?

RF works against the Fc portion of the Immunoglobulin G by forming immune complexes. These immune complexes contribute in proceeding of the disease.

Besides being an autoantibody, RF can also be a cryoglobuin. This type of antibody develops when blood sample is cooling. It could be either of type 2 cryoglobuin or type 3.

Significance

Test for presence of RHf is done if a person shows symptoms of rheumatoid arthritis. The early signs and symptoms include morning stiffness in joints, pain and formation of nodules under the skin. The RF test is one of the tests done to suggest occurrence of rheumatoid arthritis.

It is a possibility that the test may be negative for the first time even in persons with persistent RS symptoms. In such circumstances the test can eb performed again.

The RF test is also done to suggest Sjogren`s syndrome. Symptoms of this disease are dry eyes and mouth, dry skin, pain in joints and muscles.

Although RF test is a trustable test for these diseases but a negative test does not necessarily mean that RA or Sjoren`s syndrome are absent. Some patients may have low levels of RF to suggest presence of these diseases.

Also, it is only in absence of other signs and symptoms that the test confirms these diseases. Otherwise,  RH test may come positive for patients of tuberculosis, sarcoidosis, syphilis or lupus. It is also positive in patients with kidney, liver or lung diseases. It must be remembered that the test may be positive in presence of these conditions. But the test does not confirm their presence.

The Test may be Positive in These Conditions too

Presence of most of autoimmune diseases will give a positive RF test. These include mixed connective tissue disease, polymyositis, sclerodera, bacterial endocarditis, liver cirrhosis and hepatitis.