Rheumatoid arthritis is a type of chronic arthritis that typically occurs in joints on both sides of the body (such as hands, wrists, or knees). This symmetry helps distinguish rheumatoid arthritis from other types of arthritis.
In addition to affecting the joints, rheumatoid arthritis may occasionally affect the skin, eyes, lungs, heart, blood, or nerves.
What Are the Symptoms of Rheumatoid Arthritis?
Symptoms of rheumatoid arthritis include:
- 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 progress rapidly and while other people may have
rheumatoid arthritis for a limited period of time and then enter a
period of remission.
Who Gets Rheumatoid Arthritis?
Rheumatoid arthritis affects about 1% of the U.S. population. While it is two to three times more common in women than in men, men tend to be more severely affected when they get it. It usually occurs in middle age, however, young children and the elderly also can develop rheumatoid arthritis.
What Causes Rheumatoid Arthritis?
The exact cause of rheumatoid arthritis is unknown, but 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 the development of rheumatoid arthritis.
Research hasn’t completely determined exactly what role genetics plays in rheumatoid arthritis. However, 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 produce inflammatory substances. The increased number of cells and inflammatory substances within the joint cause irritation, wearing down of cartilage (cushioning material at the end of bones), and swelling and inflammation of the joint lining. Inflammation of the joint lining stimulates it to produce excessive joint fluid within the joint.
As the cartilage wears down, the space between the bones narrows. If the condition worsens, the bones could rub against each other.
As the joint lining expands, it may invade into, or erode, the adjacent bone, resulting in bone damage that is referred to as erosions. All of these factors cause the joint to become very painful, swollen, and warm to the touch.
How Is Rheumatoid Arthritis Diagnosed?