Often patients see a positive rheumatoid factor on the laboratory test, they think they have rheumatoid arthritis, this is to see the problem is too simple, because: first, strictly speaking rheumatoid factor should not only report positive or negative, but should report how much the titer is. Each hospital’s laboratory should have its own criteria for determining positivity, and rheumatoid factor without reporting titers has no reference value and can be misleading. Beijing Union Medical College Hospital 1:16 is suspicious positive, 1:32 is positive, but the diagnosis of rheumatoid arthritis is generally meaningful only at 1:64 or more. The second, normal people also have about 5% rheumatoid factor positive, the elderly positive rate is higher, up to 10% or so. Third, in addition to rheumatoid arthritis, rheumatoid factor positivity can also be seen in viral infections such as hepatitis, chronic infections such as tuberculosis, bacterial endocarditis, and other autoimmune diseases such as dry syndrome, systemic lupus erythematosus, mixed cryoglobulinemia, and many other diseases. In combination with the latest rheumatoid arthritis classification criteria in 2010, a positive rheumatoid factor is only one of the criteria, and a total score of greater than or equal to six is required to confirm a diagnosis of rheumatoid arthritis. The rheumatoid factor is not a specific indicator for the diagnosis of rheumatoid arthritis, i.e. other diseases can also show positive rheumatoid factor test results, patients suspected of rheumatoid arthritis can also check CCP, AKA, APF, rheumatoid arthritis 33, anti-Sa antibodies, etc. The reason why these indicators are checked is because the sensitivity of each indicator is different, generally only 70% – 80% or less, multiple tests can complement each other and can reduce missed diagnoses, in addition, indicators such as CCP can also have a guiding prognosis for rheumatoid arthritis, that is, the greater the value of CCP, the more serious the patient’s condition, should be actively treated.