Arthritis means inflammation in a joint. Joint inflammation causes redness, warmth, swelling, and pain within the joint.
Rheumatoid arthritis is a type of chronic arthritis that occurs in joints on both sides of the body (such as both hands, both wrists, or both knees). This symmetry helps distinguish rheumatoid arthritis from other types of arthritis.
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.
Rheumatoid arthritis may also affect the skin, eyes, lungs, heart, blood, or nerves.
What Are the Symptoms of Rheumatoid Arthritis?
Symptoms of rheumatoid arthritis are:
Joint pain and swelling
Stiffness, especially in the morning or after sitting for long periods
Rheumatoid arthritis affects everyone differently. For some, joint symptoms develop gradually over several years. In others, rheumatoid arthritis may develop quickly, while other people may have rheumatoid arthritis for a short time and then have a time with no symptoms, called remission.
Who Gets Rheumatoid Arthritis?
About 1% of Americans have rheumatoid arthritis. It is an autoimmune disease, meaning the body's immune system attacks its own healthy tissues. Rheumatoid arthritis is two to three times more common in women than in men, but men tend to have more severe symptoms. It usually happens in middle age, but young children and the elderly also can get rheumatoid arthritis.
What Causes Rheumatoid Arthritis?
The cause of rheumatoid arthritis is unknown. It is thought to be due to a combination of genetic, environmental, and hormonal factors. With rheumatoid arthritis, something seems to trigger the immune system to attack the joints and sometimes other organs. Some theories suggest that a virus or bacteria may alter the immune system, causing it to attack the joints. Other theories suggest that smoking may lead to rheumatoid arthritis.
Research hasn't found exactly what role genetics plays in rheumatoid arthritis. Some people do seem to have a genetic or inherited factor that increases their chance of developing rheumatoid arthritis.
How Does Rheumatoid Arthritis Affect the Body?
Once the immune system is triggered, immune cells migrate from the blood into the joints and joint-lining tissue, called synovium. There the immune cells make inflammatory substances that cause irritation, wearing down of cartilage (the cushioning material at the end of bones), and swelling and inflammation of the joint lining. As the cartilage wears down, the space between the bones narrows. As it gets worse, the bones could rub against each other.
Inflammation of the joint lining causes fluid to build up with the joint. As the lining expands, it may damage the bone.
All of these things cause the joint to become very painful, swollen, and warm to the touch.
How Is Rheumatoid Arthritis Diagnosed?
Rheumatoid arthritis is diagnosed from a combination of things, including:
The location and symmetry of painful joints, especially the hand joints
Joint stiffness in the morning
Bumps and nodules under the skin (rheumatoid nodules)