RA and Autoimmune Conditions: How Do You Know You Have It?

If your doctor suspects you have rheumatoid arthritis or another autoimmune condition that's affecting your joints, tests will be performed to make a diagnosis and rule out other conditions. Here's what the lab is checking when they examine your blood and synovial fluids.

Early diagnosis of arthritis, especially rheumatoid and other forms of autoimmune-based arthritis, is key to getting the best treatment and preventing or delaying disability. If you have joint pain or swelling and arthritis is suspected, your doctor can order a series of tests that will help differentiate one form of the disease from another. This way, an effective treatment plan can be initiated. In addition to a physical exam and review of medical history, your doctor may order tests for some or all of the following:

Uric Acid
High levels of uric acid in the blood, known as hyperuricemia, can be a sign of the arthritic disease known as gout. Gout is an inflammatory condition that occurs when uric acid is overproduced by the body or is not properly eliminated from the body, and crystals form in the synovial fluid of your joints. If you have gout, you're also at high risk of developing kidney stones, so detecting uric acid can help the doctor anticipate the presence of stones.

Synovial Fluid
There are other medical conditions in addition to inflammatory disorders like rheumatoid arthritis, systemic lupus, and gout that can cause joint inflammation, pain, and swelling. These include infectious diseases such as septic arthritis, joint injuries, and blood clotting disorders. The results of synovial fluid analysis will give the doctor clues to help narrow down the possibilities and rule out some of these conditions. For instance, a high protein count and an increased number of specific types of white blood cells could indicate the presence of a bacterial infection. Increased white blood cells are also seen with rheumatoid arthritis and gout. The presence of uric acid crystals could confirm gout while calcium pyrophosphate crystals in the synovial fluid may reveal a condition known as pseudogout.

Rheumatoid Factor
Another blood test, known as the rheumatoid factor (RF) test, is used to identify rheumatoid arthritis or another rheumatoid condition known as Sjögren's syndrome. Since these two conditions are difficult to diagnose because the symptoms resemble other forms of arthritis, the RF is the one test that can help the doctor make a distinction.

Initially, a CBC, or complete blood count, helps the doctor get a clear general picture of the health of your body's red and white blood cells. This test will likely be ordered along with the RF test. Other tests, such as CRP (C-reactive protein) and ESR (erythrocyte sedimentation rate) may be ordered to confirm inflammation.

The CCP, or Cyclic Citrullinated Peptide, antibody test is a newer blood test doctors can use to help clearly diagnose rheumatoid arthritis and evaluate a patient's prognosis. The CCP can be performed when the disease is simply suspected, even before symptoms clearly indicate rheumatoid arthritis. It is often ordered along with or following the RF test to help the doctor determine how serious the condition is at that point.



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Ohio State University