Rheumatoid factor (RF)

Most of the time, blood is drawn from a vein located on the inside of the elbow or the back of the hand. In infants or young children, a sharp tool called a lancet may be used to puncture the skin. The blood collects in a small glass tube called a pipette, or onto a slide or test strip. A bandage is put over the spot…

You do not need to take special steps before this test.

You may feel slight pain or a sting when the needle is inserted. You may also feel some throbbing at the site after the blood is drawn.

This test is most often used to help diagnose rheumatoid arthritis or Sjögren syndrome .

Results are usually reported in one of two ways: Value, normal less than 15 IU/mL Titer, normal less than 1:80 (1 to 80) If the result is above the normal level, it is positive. A low number (negative result) most often means you do not have rheumatoid arthritis or Sjögren syndrome. However, some people who do have…

An abnormal result means the test is positive, which means a higher level of RF has been detected in your blood. Many people with rheumatoid arthritis or Sjögren syndrome have positive RF tests. The higher the level, the more likely one of these conditions is present. There are also other tests that can be done to…

Aletaha D, Neogi T, Silman AJ, et al. 2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Ann Rheum Dis . 2010;69(9):1580-1588. PMID: 20699241 pubmed.ncbi.nlm.nih.gov/20699241/ . Darrah E, Rosen A, Andrade F. Autoantibodies…