Lupus is an autoimmune disease, which means that the immune system mistakes the body's own tissues as foreign invaders and attacks them. Some people with lupus suffer only minor inconvenience. Others suffer significant lifelong disability.
Lupus affects people of African, Asian, or Native American descent two to three times as often as it affects whites. Nine out of 10 people with lupus are women. The disease usually strikes between age 15 and 44, although it can occur in older individuals.
Lupus is a difficult disease to diagnose because its symptoms can be vague. And unlike some other diseases, it cannot be diagnosed with a single lab test. However, when certain clinical criteria are met, lab tests can help confirm a diagnosis of lupus. Blood work and other tests can also help monitor the disease and show the effects of treatment.
WebMD takes a look at the uses and limitations of the tests that are commonly used to diagnose and monitor lupus.
DLE mainly affects skin that is exposed to sunlight and doesn’t typically affect vital internal organs. Discoid (circular) skin lesions often leave scars after healing of the lesions.
SLE is more serious: It affects the skin and other vital organs, and can cause a raised, scaly, butterfly-shaped rash across the bridge of the nose and cheeks that can leave scars if untreated. SLE can also affect other parts of the skin elsewhere on the body.
Aside from the visible effects of systemic lupus, the disease may also inflame and/or damage the connective tissue in the joints, muscles, and skin, along with the membranes surrounding or within the lungs, heart, kidneys, and brain. SLE can also cause kidney disease. Brain involvement is rare, but for some, lupus can cause confusion, depression, seizures, and strokes.
Blood vessels may come under attack with systemic lupus. This can cause sores to develop on the skin, especially the fingers. Some lupus patients get Raynaud's syndrome, which makes the small blood vessels in the skin contract, preventing blood from getting to the hands and feet -- especially in response to cold. Most attacks last only a few minutes, can be painful, and often turn the hands and feet white or a bluish color. Lupus patients with Raynaud’s syndrome should keep their hands warm with gloves during cold weather.
What Causes Lupus?
No single factor is known to cause lupus. Research suggests that a combination of genetic, hormonal, environmental, and immune system factors may be behind it. Environmental factors, ranging from viral and bacterial infections to severe emotional stress or overexposure to sunlight, may play a role in provoking or triggering the disease. Certain drugs, such as the blood pressure drug hydralazine and the heart rhythm drug procainamide, may cause lupus-like symptoms. High estrogen levels resulting from pregnancy may aggravate lupus.