The normal range for RF factor in the blood is typically less than 40 to 60 units per milliliter, according to MedlinePlus. Some labs may also report it as a titer of less than 1 to 80. Testing for rheumatoid factor requires giving a blood sample.
The RF test is used to help diagnose rheumatoid arthritis or Sjogren's syndrome. A low RF can mean a patient does not have those conditions, but some people with rheumatoid arthritis or Sjogren's syndrome have a normal amount of RF in the blood, states MedlinePlus. The higher the RF level, the more likely the patient has one of the two conditions.