Rheumatoid factor (RF) test checks for the presence of a particular antibody that appears in the blood of the majority of people who have RA. But a positive RF test doesn’t necessarily mean you have rheumatoid arthritis. The RF antibody can also appear due to other rheumatic diseases, hepatitis C, and many other medical conditions.

       Erythrocyte sedimentation rate (ESR or sed rate) measures the rate at which red blood cells settle in a test tube, which can indicate inflammation.This is a nonspecific marker of inflammation, which may be due to several factors, including age, obesity, infection, cancer, and autoimmune conditions.

       C-reactive protein (CRP) is another nonspecific marker of inflammation. It checks for a protein that indicates inflammation is present somewhere in the body.

       Cyclic citrullinated peptide (CCP) antibody checks for a type of antibody commonly produced in rheumatoid arthritis as well as certain other autoimmune disorders.

       Complete blood count (CBC) checks for anemia (meaning there are not enough red blood cells) and thrombocytosis (the production of too many platelets), both of which can occur with chronic inflammation and are often seen in RA. These findings are not specific to RA, just a sign of chronic inflammation.

       Antinuclear antibody (ANA) checks for antibodies to components in the nucleus of cells. This is very nonspecific test that is commonly positive in healthy individuals (up to 25 percent at low levels!), but may provide additional clues that you have RA, or another condition such as lupus.

       Human leukocyte antigen tissue typing (HLA) checks for a genetic marker that indicates an increased likelihood for developing an immune-related condition like RA, reactive arthritis, or ankylosing spondylitis. HLAB27 is the test most commonly ordered, but is not routinely needed to evaluate someone for RA.

       Joint aspiration (arthrocentesis): The doctor inserts a needle into your affected joint(s) to remove some of the synovial fluid, which is examined under a microscope for evidence of infection or inflammation.

       Imaging tests: A standard X-ray of your joints may be taken to check for bone and cartilage loss and/or serve as a baseline for comparison of future X-rays.However, X-rays aren’t sensitive enough to detect joint damage in the early stages of the disease. Magnetic resonance imaging (MRI) and ultrasound images may be helpful in detecting early signs of RA when the diagnosis is not clear since they can provide more information than X-ray, but aren’t always needed to make an RA diagnosis. Computerized technology (CT scans) are rarely used to detect RA because, although they show bone damage, they lack the sensitivity to reveal soft-tissue changes.

       Biopsy of rheumatoid nodules: Rheumatoid nodules are rubbery lumps under the skin that often form near the joints in people who have RA. Occasionally, a biopsy will be done to rule out other conditions, like infections or gout. However, this is not a very common procedure.Unless the rheumatoid nodules cause pain or impair your range of motion, they usually don’t need to be treated. But since other bumps and lumps can look and feel like RA nodules, your doctor may want to take a piece of tissue from one of them and examine it under a microscope to confirm the diagnosis. After carefully cleansing the skin and injecting a local anesthetic, the doctor makes a tiny cut near the nodule and, if possible, shaves off a piece of tissue. Or they may push a thin, hollow needle into the nodule and, using suction, pull out a tissue sample.