Diagnosing rheumatoid arthritis

DEAR DOCTOR K: My doctor suspects I have rheumatoid arthritis, but she wants to test me for several other disorders, including lupus and gout. Why?

DEAR READER: Several other diseases can cause symptoms and joint changes that are similar to rheumatoid arthritis (RA), including lupus and gout.

RA is an autoimmune disease. The body’s immune system attacks healthy tissue, primarily the tissue lining the joints. This causes swelling, pain, redness and stiffness in the joints. RA can affect other tissues throughout the body as well.

Accurately diagnosing RA, especially in the early stages, can be difficult. A physical exam, your symptoms, blood tests and imaging tests can all help. But before finalizing the diagnosis, your doctor may want to rule out other possibilities, including:

• LUPUS is an inflammatory autoimmune disease. Fever and joint pain are common early symptoms of lupus, just as they are for RA. The joints involved in lupus often are the same ones affected in RA.

• SCLERODERMA is an autoimmune disease that causes skin to thicken, tighten and look shiny. Some people have rheumatoid-like arthritis; others have a combination of arthritis and tightening of the tendons.

• SJOGREN’S SYNDROME is also an autoimmune disease. Immune system cells tend to attack the tear and saliva glands, causing dry eyes and dry mouth. The disease may also cause joint pain and swelling that mimics RA.

• GOUT. This form of arthritis develops after tiny crystals of uric acid accumulate in joints, causing the joints to become swollen, red and very painful.

• PSEUDOGOUT is similar to gout, but results from deposits of certain kinds of crystals (made of calcium pyrophosphate) in joints. Long-standing pseudogout can resemble RA.

• OSTEOARTHRITIS. The joint pain of osteoarthritis can be similar to that caused by RA. However, there are significant differences between other symptoms and the causes of the two conditions.