The tests used are ESR (sedimentation rate of speed, also called and erythrocyte sedimentation rate), C-reactive protein and less often alpha-1 acid glycoprotein. They tend to be high in proportion to the severity of the disease and decrease with successful treatment. Do not forget that these tests are not specific. May be high in any disease that causes inflammation or infection.
The rheumatoid factor (RF) is the most striking immunologic abnormality of the AR. Appears in 80% of patients and therefore used as a diagnostic criterion for first line. However, besides not being present in 20% of patients with RA, it may take up to 1 year to become positive. Another important fact about the FR is its presence in other rheumatic and non-rheumatic such as chronic active hepatitis, viral hepatitis, leprosy, tuberculosis, malignancies and several others. In these cases, in general, the titre (concentration) is usually lower.
The test result should be a number. It is suggested not to accept tests expressed in crosses or only positive or negative.
Investigations described recently, perinuclear factor and anti-keratin, are less often positive but may be the only early changes and thus provide early diagnosis of the disease. This fact is important for the correct treatment is started immediately, avoiding the deformities already mentioned.
Complete blood count, platelets, transaminases and standard urine test are required to be able to assess the effects of the drugs. Lately, research on hepatitis viruses (especially hepatitis C) have been included in the initial assessment and, possibly, during evolution.
Also needed are tests to assess involvement of the kidneys and liver and others that the initial evaluation or the disease state.