November 26, 2015
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Rheumatoid Arthritis (cont.)

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What are causes and risk factors of rheumatoid arthritis?

The cause of rheumatoid arthritis is unknown. Even though infectious agents such as viruses, bacteria, and fungi have long been suspected, none has been proven as the cause. The cause of rheumatoid arthritis is a very active area of worldwide research. It is believed that the tendency to develop rheumatoid arthritis may be genetically inherited (hereditary). Certain genes have been identified that increase the risk for rheumatoid arthritis. It is also suspected that certain infections or factors in the environment might trigger the activation of the immune system in susceptible individuals. This misdirected immune system then attacks the body's own tissues. This leads to inflammation in the joints and sometimes in various organs of the body, such as the lungs or eyes.

It is not known what triggers the onset of rheumatoid arthritis. Regardless of the exact trigger, the result is an immune system that is geared up to promote inflammation in the joints and occasionally other tissues of the body. Immune cells, called lymphocytes, are activated and chemical messengers (cytokines, such as tumor necrosis factor/TNF, interleukin-1/IL-1, and interleukin-6/IL-6) are expressed in the inflamed areas.

Gut Bacteria, Smoking, and Gum Disease

Environmental factors also seem to play some role in causing rheumatoid arthritis. For example, scientists have reported that smoking tobacco, exposure to silica mineral, and chronic periodontal disease all increase the risk of developing rheumatoid arthritis. There are theories about different gut bacteria (microbes that inhabit the lining of the bowels) that might trigger the onset of rheumatoid arthritis in genetically susceptible individuals. No specific microbes have been identified as definite causes.

What are complications of rheumatoid arthritis?

Since rheumatoid arthritis is a systemic disease, its inflammation can affect organs and areas of the body other than the joints. Inflammation of the glands of the eyes and mouth can cause dryness of these areas and is referred to as Sjögren's syndrome. Dryness of the eyes can lead to corneal abrasion. Inflammation of the white parts of the eyes (the sclerae) is referred to as scleritis and can be very dangerous to the eye. Rheumatoid inflammation of the lung lining (pleuritis) causes chest pain with deep breathing, shortness of breath, or coughing. The lung tissue itself can also become inflamed and scarred, and sometimes nodules of inflammation (rheumatoid nodules) develop within the lungs. Inflammation of the tissue (pericardium) surrounding the heart, called pericarditis, can cause a chest pain that typically changes in intensity when lying down or leaning forward. Rheumatoid arthritis is associated with an increased risk for heart attack. Rheumatoid disease can reduce the number of red blood cells (anemia) and white blood cells. Decreased white cells can be associated with an enlarged spleen (referred to as Felty's syndrome) and can increase the risk of infections. The risk of lymph gland cancer (lymphoma) is higher in patients with rheumatoid arthritis, especially in those with sustained active joint inflammation. Firm lumps or firm bumps under the skin (subcutaneous nodules called rheumatoid nodules) can occur around the elbows and fingers where there is frequent pressure. Even though these nodules usually do not cause symptoms, occasionally they can become infected. Nerves can become pinched in the wrists to cause carpal tunnel syndrome. A rare, serious complication, usually with longstanding rheumatoid disease, is blood vessel inflammation (vasculitis). Vasculitis can impair blood supply to tissues and lead to tissue death (necrosis). This is most often initially visible as tiny black areas around the nail beds or as leg ulcers.

Medically Reviewed by a Doctor on 11/12/2015



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