What Do You Have?
There are about 100 different types of arthritis. These tests can help doctors distinguish two major forms: osteoarthritis and rheumatoid arthritis.
OSTEOARTHRITIS
Medical history . The disease often affects the hips, knees, and lower back. It usually starts with a joint on one side of the body, not both. In the morning, people feel stiff for a few minutes, rather than for several hours.
Tests. Blood tests are not very helpful. Nor are X-rays. But one test, a fluid sample from the joint, may help rule out other diseases.
RHEUMATOID ARTHRITIS
Medical history . Hands, wrists, and feet are often affected, on both sides of the body. They look red. Patients can feel tired. And morning stiffness often lasts for hours.
Tests. Blood tests can reveal signs of inflammation, a hallmark of the disease. Many people also have a substance called rheumatoid factor in the blood, though children often don't. A joint-fluid sample may reveal a high number of white blood cells, another sign.
This story appears in the June 27, 2005 print edition of U.S. News & World Report.