Blood Tests for Diagnosing Rheumatoid Arthritis (RA)
There is no single test for diagnosing RA. Your doctor will order several different tests. He will use his experience and judgment to decide if they may indicate a diagnosis of RA.
Erythrocyte Sedimentation Rate or ESR
This is more of a general test for inflammation in your body. If your ESR is high it means that something is causing inflammation.
It may or may not be RA, but it will tell your doctor he needs to investigate further.
Rheumatoid Factor is a test that is often used for diagnosing rheumatoid arthritis. It is testing for a specific antibody against a blood component called gamma globulin.
It was first discovered to be related to RA but further research has found that this test is also positive in other autoimmune diseases such as lupus and sarcoidosis.
Blood tests can be helpful for diagnosing rheumatoid arthritis but there is not any one test that proves you have RA.
Image thanks to U.S.Navy, via Wikimedia Commons
Anti-Nuclear Antibody is an abnormal antibody that attacks the nucleus of cells.
It is often found in many autoimmune diseases such as lupus, Sjogren’s syndrome, and polymyositis.
This is another test for antibodies that are attacking your bodies normal tissue. This antibody will attach to a protein in your blood called cyclic citrullinated peptides. This is found in 50-60% of people with RA and can often be positive early in the disease when other tests are still negative.
Image thanks Wikimedia Commons
Examine all of Your Joints
If you are complaining of morning stiffness and pain in certain joints your doctor may suspect RA especially if the painful joints are in your wrists, hands, or fingers.
Your doctor will also be looking for Rheumatoid Nodules. These are hard lumps that form under your skin.
They can be as small as a pea or as large as a walnut. They are most commonly found around your elbows, wrists, hands and fingers.
Imaging Studies for RA
X-rays, MRIs, and CT scans are often not helpful for the initial diagnosis. They are usually normal until late in the disease after joint damage has occurred.
If You have RA
Your doctor will combine his findings on your physical exam with the results of the blood tests to determing how likely it is that you have RA.
If he thinks that you have RA he may start you on some medications for treatment or he may refer you to a rheumatologist (a doctor that specializes in treating autoimmune diseases).