Diagnosing arthritis may be difficult. There are more than 100 different types of arthritis. Many symptoms are similar among the different conditions affecting the joints. Arthritis may be generally categorized into the following groups: degenerative arthritis, inflammatory arthritis, metabolic arthritis, and infectious arthritis. Osteoarthritis (also known as degenerative arthritis) is the most common type. Rheumatoid arthritis and gout are two other more common types. To make an accurate diagnosis, a healthcare provider may need to:

• Review your medical history and current symptoms.

• Examine you, paying close attention to your joints.

• Order laboratory tests, X-rays, and other imaging tests (such as an ultrasound or MRI).

• Perform an arthrocentesis (the procedure of removing fluid from a joint).

What is involved in reviewing your medical history and your current symptoms?

When reviewing your medical history, your healthcare provider may ask the following questions:

• Have you had any illnesses or injuries that may explain the pain?

• Is there a family history of arthritis or other rheumatic diseases?

• What medication(s) are you currently taking?

Your healthcare provider may also ask:

• What symptoms are you having? For example, pain, stiffness, difficulty with movement, or swelling.

• About your pain:

  • Where is it?

  • How long have you had it?

  • When do you have pain and how long does it last?

  • Describe your pain. (Constant, dull, throbbing, stabbing)

  • How intense is it? (on a scale of 1 to 10, with 1 being no pain, and 10, the worst pain)

  • What lessons the pain?

  • What makes it worse?

What is involved in laboratory testing?

In addition to a complete medical history and physical examination, the following are common laboratory tests:

• Antinuclear antibody. This test measures blood levels of various antibodies, which may be present in persons with some types of arthritis.

• Arthrocentesis (also called joint aspiration). This is an exam of joint fluid. A thin needle is inserted into the joint. Synovial fluid is removed with a syringe and examined for cell counts, crystal analysis, culture, and other tests.

• Complement tests. This test measures the level of complement, a group of proteins in the blood. It is used to help diagnose and monitor systemic lupus erythematosus (SLE) and rheumatoid arthritis.

• Complete blood count. Measures the number of white blood cells, red blood cells, and platelets present in a sample of blood. A low white blood count (leukopenia), low red blood count (anemia), or low platelet count (thrombocytopenia) are associated with some forms of arthritis or the medications to treat them.

• Creatinine. A blood test to monitor for underlying kidney disease.

• C-reactive protein. This is a protein that is elevated when there is inflammation in the body as in some types of arthritis.

• Erythrocyte sedimentation rate (also called ESR or sed rate). This measures how quickly red blood cells fall to the bottom of a test tube. It is also elevated when there is inflammation in the body. This occurs in some types of arthritis.

• Hematocrit (PCV, packed cell volume). Measures the number of red blood cells present in a sample of blood. Low levels of red blood cells (anemia) are common in people with some types of arthritis.

• Rheumatoid factor. Checks for an antibody that is present in most people with rheumatoid arthritis.

• Urinalysis. Laboratory examination of urine to check for kidney disease that may be associated with several types of arthritis.

• Uric acid. It is elevated in gout.

What imaging techniques may be used to diagnose arthritis?

Imaging techniques may give your healthcare provider a clearer picture of what is happening to your joint(s). Imaging techniques may include the following:

• X-ray. X-rays may show joint changes and bone damage found in some types of arthritis. Other imaging tests may also be done.

• Ultrasound. Ultrasound uses sound waves (not radiation) to see the quality of synovial tissue, tendons, ligaments, and bones.

• Magnetic resonance imaging (MRI). MRI images are more detailed than X-rays. They may show damage to joints, including muscles, ligaments, and cartilage.

• Arthroscopy. This procedure uses a thin tube containing a light and camera (arthroscope) to look inside the joint. The arthroscope is inserted into the joint through a small incision. Images of the inside of the joint are projected onto a screen. It is used to evaluate any degenerative and/or arthritic changes in the joint; to detect bone diseases and tumors; to determine the cause of bone pain and inflammation, and to treat certain conditions.