What is lupus?
Systemic lupus erythematosus (lupus) is a disease of the immune system. Normally, the immune system protects the body from infection. However, in lupus, the immune system inappropriately attacks tissues in various parts of the body. This abnormal activity of the immune system leads to tissue damage and illness.
Who is affected by lupus?
Lupus can affect men and women of any race or age. One in 2,000 people in the United States has lupus. People of African, Asian and Native American descent are more likely to develop lupus than are Caucasians.
Areas of the body which may be affected during the course of lupus are shown in this drawing. The blood may also be affected.
If only women of childbearing age (14 to 45 years old) are considered, as many as 1 in 250 may develop lupus. This suggests a possible role for female hormones influencing vulnerability to this disease.
What problems may lupus patients develop?
Many patients with active lupus feel poorly in general and complain of fever, weight loss and tiredness. Patients with lupus also develop specific problems when the immune system attacks a particular organ(s) or area(s) in the body.
Specific areas of the body that may be affected during the course of lupus include the skin, joints, and kidneys. The blood may also be affected during the course of lupus, resulting in low red blood cell count (anemia), low white blood cell count and low platelet count.
Skin problems are a common feature of lupus. Some patients with lupus have a red rash over their cheeks and the bridge of their nose. Because the location of this rash is the same as the common markings of a wolf, the name "lupus" (wolf in Latin) was given to this disease many years ago.
Other skin problems that occur include large red, circular rashes (plaques), which may scar (called discoid lupus). Skin rashes are usually aggravated by sunlight.
Hair loss and mouth sores are also common.
Arthritis is very common in people who have lupus. There may be pain, with or without swelling. Stiffness and pain may be especially evident in the morning. Arthritis may be a problem for only a few days to weeks or may be a permanent feature of the disease. Fortunately, arthritis is usually not crippling.
Kidney involvement in people with lupus is potentially life threatening and may occur in up to half of lupus patients. Kidney problems may become apparent when lupus patients feel ill with arthritis, have a rash, fever and weight loss. Less often, kidney disease may occur when there are no other symptoms of lupus. Kidney disease itself usually does not produce symptoms until it is in the advanced stages. It is important that kidney disease be diagnosed early and treated appropriately. The earliest signs of kidney disease are apparent from a urinalysis.
Blood involvement can occur with or without other symptoms. Patients may have dangerous reductions in the number of red blood cells, white blood cells or platelets (cells that help clot the blood).
Sometimes changes in blood counts may contribute to symptoms of fatigue (low red blood cell count, anemia), serious infections (low white blood cell count), or easy bruising (low platelet count). However, many patients do not have symptoms that indicate blood abnormalities, so it is important for lupus patients to have periodic blood tests in order to detect any problems.
Blood clots are seen with increased frequency in lupus. Clots often occur in the legs (a vein clot, called deep venous thrombosis), lungs (a lung clot, called pulmonary embolus), or brain (stroke). Blood clots that develop in lupus patients may be associated with the production of antiphospholipid antibodies. These antibodies are abnormal proteins that may increase the tendency of the blood to clot.
Heart and lungs
Heart and lung involvement is often caused by inflammation of the covering of the heart (pericardium) and lungs (pleura). When these structures become inflamed, patients may develop chest pain, irregular heartbeat and accumulation of fluid around the lungs (pleuritis or pleurisy) and heart (pericarditis).
What causes lupus?
The cause of lupus is unknown. Finding the cause is the object of major research efforts.
Factors that may contribute to the cause of lupus include viruses, environmental chemicals, and the person's genetic makeup.
Female hormones are believed to play a role in the development of lupus because women are affected more commonly than men. This is especially true of women during their reproductive years, a time when hormone levels are highest.
The observation that lupus may affect more than one member of the same family has raised the possibility that the tendency to develop lupus may be inherited. Having such a tendency, however, does not predict that a relative will develop lupus. About 10 percent of lupus patients have a close relative with lupus.