The rheumatoid factor test is a commonly ordered test to help diagnose rheumatoid arthritis. This test measures rheumatoid factor, which is an antibody in the blood that's present in many people with RA. In fact, the rheumatoid factor blood test is eventually positive in 70% to 80% of people with RA, although in early arthritis the percentage may be much smaller. Rheumatoid factor may also be elevated in other autoimmune diseases besides RA.
"Arthritis is common, and rheumatoid arthritis often gets confused with the other kinds of arthritis in people's minds,” he says.
Plus, rheumatoid arthritis is still mysterious in many ways. Research and new treatments are constantly changing the understanding of the disease.
Even the experts still have a lot to learn about rheumatoid arthritis. WebMD teamed up with Kremer to explode a few common myths about this "commonly unusual" disease.
Myth No. 1: Rheumatoid arthritis is just like ‘regular arthritis.’
Fact: Rheumatoid arthritis is not "regular arthritis." What we think of as “regular arthritis” is osteoarthritis, caused by injury or normal wear-and-tear on aging joints. Osteoarthritis is the most common joint disease in middle age to older people.
By contrast, rheumatoid arthritis is a chronic, progressive autoimmune disorder. In response to an unknown trigger, the body makes antibodies that attack its own tissues. The self-attacks mostly affect the joints, although they can also affect other body parts. Disease attacks, called flare-ups, occur periodically, or can be continuous in some people.
"This is the most common confusion -- between osteoarthritis and rheumatoid arthritis. It gets even more confusing, because people with RA often also have osteoarthritis," adds Kremer.
Myth No. 2: Only old people get rheumatoid arthritis.
Fact: In most people who develop RA, the disease starts between the ages of 30 and 55.
"This is the peak age group," says Kremer, "but anyone can get rheumatoid arthritis, even teenagers." At the same time, "older folks may have more severe RA, because it's progressive and they've been living with it longer."
Myth No. 3: Rheumatoid arthritis isn't all that serious.
Fact: Rheumatoid arthritis can threaten your health and independence, especially if it's inadequately treated.
"A lot of people downplay RA as just 'Grandma's rheumatism,' and they miss the boat completely," says Kremer. "They delay seeing a physician, often for months or years, and a lot of joint damage can happen during that time."
Rheumatoid arthritis needs prompt diagnosis and regular treatment to protect joints from harm. In turn, this can protect your independence and long-term function.
Having rheumatoid arthritis also increases the risk for certain other conditions, says Kremer. “Cardiovascular diseases, infections, and lung disease are all more common in people with RA."