A rheumatoid arthritis factor (RF) test is generally recommended when doctors want to diagnose rheumatoid arthritis. As the name implies, the test measures the level of this factor in the blood and draws premises based on the readings derived.
Simply put, this is an antibody produced naturally within the body. Antibodies are agents that fight infection. However these factors are not typically seen in most people. Only 1-2% of healthy people have it.
It is true that this antibody is found in a good percentage of patients diagnosed with rheumatoid arthritis. Higher levels could be taken as an indication of the disease.
That is why patients are filled with fear when they are told that their readings are above normal. So, it is easy to assume that a high reading automatically suggests development of the disease. But, this is not true.
The reading for this factor is ordinarily low in most normal individuals. However, their number increases due to a number of reasons like viral fever or chronic bacterial infection.
Sometimes, healthy individuals above the age of 65 may also have the rheumatoid factor.
Typically though, high levels of this factor indicate that the patient is suffering from severe bone and joint damage.
A doctor can determine the factor through a quick and virtually painless blood test. Blood collected from the vein is sent for analysis.
Results help doctors diagnose the disease more accurately. The result of the test may be used in conjunction with other blood tests and MRI scans to ascertain the disease.
The test also shows whether the disease is progressing aggressively or not. Higher levels of the factor may be linked to a higher tendency to develop non-joint complications too, like rheumatoid nodules or lung disease.
However, the number may be high in a number of diseases, like:
In rare cases, it has also been seen that cancer patients too show positive readings.
Certain conditions are not associated with higher levels of this factor. They include common diseases like osteoarthritis, gout, psoriatic arthritis and ankylosing spondylosis.
Rheumatoid arthritis factor test in itself is not conclusive proof of rheumatoid arthritis. The results of this test are used in combination with other tests, depending on the condition of the individual.
For instance, the doctor may also recommend a complete CBC test or a CRP test along with imaging tests before they complete their diagnosis of the condition.