Rheumatoid Arthritis (cont.)

How Is Rheumatoid Arthritis Diagnosed?

Rheumatoid arthritis can be difficult to diagnose in its early stages for several reasons. First, there is no single test for the disease. In addition, symptoms differ from person to person and can be more severe in some people than in others. Also, symptoms can be similar to those of other types of arthritis and joint conditions, and it may take some time for other conditions to be ruled out. Finally, the full range of symptoms develops over time, and only a few symptoms may be present in the early stages. As a result, doctors use a variety of the following tools to diagnose the disease and to rule out other conditions:

Medical history: The doctor begins by asking the patient to describe the symptoms, and when and how the condition started, as well as how the symptoms have changed over time. The doctor will also ask about any other medical problems the patient and close family members have and about any medications the patient is taking. Accurate answers to these questions can help the doctor make a diagnosis and understand the impact the disease has on the patient's life.

Good communication between patient and doctor is especially important. For example, the patient's description of pain, stiffness, and joint function and how these change over time is critical to the doctor's initial assessment of the disease and how it changes over time.

Physical examination: The doctor will check the patient's reflexes and general health, including muscle strength. The doctor will also examine bothersome joints and observe the patient's ability to walk, bend, and carry out activities of daily living. The doctor will also look at the skin for a rash and listen to the chest for signs of inflammation in the lungs.

Laboratory tests: A number of lab tests may be useful in confirming a diagnosis of rheumatoid arthritis. Following are some of the more common ones:

  • Rheumatoid factor (RF): Rheumatoid factor is an antibody that is present eventually in the blood of most people with rheumatoid arthritis. (An antibody is a special protein made by the immune system that normally helps fight foreign substances in the body.) Not all people with rheumatoid arthritis test positive for rheumatoid factor, and some people test positive for rheumatoid factor, yet never develop the disease. Rheumatoid factor also can be positive in some other diseases; however, a positive RF in a person who has symptoms consistent with those of rheumatoid arthritis can be useful in confirming a diagnosis. Furthermore, high levels of rheumatoid factor are associated with more severe rheumatoid arthritis.
  • Anti-CCP antibodies: This blood test detects antibodies to cyclic citrullinated peptide (anti-CCP). This test is positive in most people with rheumatoid arthritis and can even be positive years before rheumatoid arthritis symptoms develop. When used with the RF, this test's results are very useful in confirming a rheumatoid arthritis diagnosis.
  • Others: Other common laboratory tests include a white blood cell count, a blood test for anemia, which is common in rheumatoid arthritis; the erythrocyte sedimentation rate (often called the sed rate), which measures inflammation in the body; and C-reactive protein, another common test for inflammation that is useful both in making a diagnosis and monitoring disease activity and response to anti-inflammatory therapy.

X rays: X rays are used to determine the degree of joint destruction. They are not useful in the early stages of rheumatoid arthritis before bone damage is evident; however, they may be used to rule out other causes of joint pain. They may also be used later to monitor the progression of the disease.