Rheumatoid Arthritis Tests & Diagnosis
Rheumatoid Factor Test
Rheumatoid factor (RF) is an antibody, which is a protein in the body. The majority of patients with rheumatoid arthritis will have a positive RF test. Less than one-fourth of rheumatoid arthritis patients will not test positive for RF. This type of test is called seronegative. The opposite can also occur: people may have a positive RF test even when they do not have rheumatoid arthritis.
Anti-CCP Antibody Test
Anti-cyclic citrullinated peptide antibody (anti-CCP) is a type of blood test that doctors use to diagnose rheumatoid arthritis. Most doctors will conduct an anti-CCP antibody test in conjunction with a rheumatoid factor test in order to obtain more conclusive and precise results.
Anti-citrullinated protein/peptide antibodies are antibodies, like RF, that are present in patients with rheumatoid arthritis.
This test is effective in diagnosing rheumatoid arthritis patients who do not test positive for RF.
A doctor will conduct a variety of additional blood tests when diagnosing rheumatoid arthritis. The main reason is that a variety of underlying conditions can produce rheumatoid arthritis symptoms. The doctor will check your renal function, liver enzymes, ferritin, and immune system. The doctor will pay particular attention to tests that indicate the presence of lupus, liver damage, hemochromatosis, Still's Disease, and Sjögren's syndrome.
Joint Fluid Analysis
Doctors perform synovial fluid analyses to diagnose the reason for joint inflammation, pain, swelling, and fluid. This type of test can help diagnose rheumatoid arthritis and rule out other inflammatory conditions that produce similar symptoms. This type of test can diagnose crystal formation, gout, lupus, osteoarthritis, and erythematosus.
Normally, joint fluid contains glucose, proteins, white blood cells, and red blood cells. In the presence of a degenerative condition, abnormalities will be evident. Normal synovial fluid is clear, viscous, with a slight beige color. An abnormality will cause the joint fluid to look less viscous, cloudy, or red if there is blood presence. Doctors might also choose to see whether glucose levels are high or low, or whether there are proteins that indicate a bacterial infection. High amounts of uric acid may be symptoms of gout, another type of arthritis.
CT, MRI, and X-ray scans indicate whether the joints and bones are degenerating. If you have been diagnosed with rheumatoid arthritis, you may need to undergo regular scans to make sure that your condition has not become severe. MRI scans can help detect whether the swelling has caused any neurological problems, such as a pinched nerve.
The American College of Rheumatology is an organization that specializes in rheumatoid arthritis research. More than two decades ago, the organization developed guidelines for diagnosing rheumatoid arthritis. A patient must meet at least four criteria to become diagnosed with rheumatoid arthritis:
- Morning stiffness for more than one hour for at least a month and a half
- Arthritis and swelling of at least three joints for six weeks
- Arthritis in the joints of the hand for a month and a half
- Symmetric arthritis for a month and a half
- Subcutaneous nodules
- RF levels above the 95th percentile
- Joint degeneration that is visible through X-rays
Sometimes, rheumatoid arthritis can be difficult to diagnose, especially when similar conditions are possible. Conditions that are similar to rheumatoid arthritis include:
- Crystal induced arthritis, which affects particular joints. You can distinguish these conditions based on joint fluid tests.
- Osteoarthritis, which can result from age and injury
- Lupus, which can be indentified using blood tests
- Lyme disease, which is caused by a bacterial infection from an insect bite. Additional blood tests can distinguish Lyme disease from rheumatoid arthritis.
- Gonococcal arthritis, which can affect the tendons around the wrist.
Based on your symptoms, a doctor may want to test for a variety of conditions at once using a blood test or joint fluid test. For diagnostic and treatment purposes, it is important that you maintain an accurate record of your symptoms. There are more than 100 different types of arthritis that can potentially cause similar symptoms to rheumatoid arthritis.
Your doctor will conduct tests based on your symptoms and medical history. In some situations, the doctor may need to conduct tests in order to assess what damage has already occurred. You may need additional heart and neurological tests to determine an effective and personalized treatment plan.