Definition
Lupus is an autoimmune disease. Your body’s immune system is like an army with hundreds of soldiers. The immune system’s job is to fight foreign substances in the body, like germs and viruses. But in autoimmune diseases, the immune system is out of control. It attacks healthy tissues, not germs. You can’t catch lupus from another person. It isn’t cancer, and it isn’t related to AIDS. The majority of lupus cases occur in women, and African-American women are more likely to have lupus than Caucasian women.
Lupus is a disease that can affect many parts of the body. Everyone reacts differently. One person with lupus may have swollen knees and fever. Another person may be tired all the time or have kidney trouble. Someone else may have rashes. Lupus can involve the joints, the skin, the kidneys, the lungs, the heart, and/ or the brain. If you have lupus, it may affect two or three parts of your body. Usually, one person doesn’t have all the possible symptoms.
There are three main types of lupus:
- Systemic lupus erythematosus (eh-RITH-eh-muh-TOE-sus) is the most common form. It’s sometimes called SLE, or just lupus. The word “systemic” means that the disease can involve many parts of the body such as the heart, lungs, kidneys, and brain. SLE symptoms can be mild or serious.
- Discoid lupus erythematosus mainly affects the skin. A red rash may appear, or the skin on the face, scalp, or elsewhere may change color.
- Drug-induced lupus is triggered by a few medicines. It’s like SLE, but symptoms are usually milder. Most of the time, the disease goes away when the medicine is stopped. More men develop drug-induced lupus because the drugs that cause it, hydralazine and procainamide, are used to treat heart conditions that are more common in men.
Alternative Names
Systemic lupus erythematosus
Causes
Lupus is a complex disease, and its cause is unknown. Scientists are making progress in understanding the condition.
In studies of identical twins—who are born with the exact same genes—when one twin has lupus, the other twin has a 24-percent chance of developing it. This and other research suggests that genetics plays an important role, but it also shows that genes alone do not determine who gets lupus, and that other factors play a role. Some of the factors scientists are studying include sunlight, stress, hormones, cigarette smoke, certain drugs, and infectious agents such as viruses. Recent research has confirmed that one virus, Epstein-Barr virus (EBV), which causes mononucleosis, is a cause of lupus in genetically susceptible people.
Scientists believe there is no single gene that predisposes people to lupus. Rather, studies suggest that a number of different genes may be involved in determining a person’s likelihood of developing the disease, which tissues and organs are affected, and the severity of disease. Researchers have begun to make headway in identifying some of those genes, which could eventually lead to better ways to treat and perhaps even prevent lupus.
In lupus, the body’s immune system does not work as it should. A healthy immune system produces proteins called antibodies and specific cells called lymphocytes that help fight and destroy viruses, bacteria, and other foreign substances that invade the body. In lupus, the immune system produces antibodies against the body’s healthy cells and tissues. These antibodies, called autoantibodies, contribute to the inflammation of various parts of the body and can cause damage to organs and tissues. The most common type of autoantibody that develops in people with lupus is called an antinuclear antibody (ANA) because it reacts with parts of the cell’s nucleus (command center). Doctors and scientists do not yet understand all of the factors that cause inflammation and tissue damage in lupus, and researchers are actively exploring them.
Symptoms
Lupus may be hard to diagnose. It’s often mistaken for other diseases. For this reason, lupus has been called the “great imitator.” The signs of lupus differ from person to person. Some people have just a few signs; others have more.
Common signs of lupus are:
- Red rash or color change on the face, often in the shape of a butterfly across the nose and cheeks
- Painful or swollen joints
- Unexplained fever
- Chest pain with deep breathing
- Swollen glands
- Extreme fatigue (feeling tired all the time)
- Unusual hair loss (mainly on the scalp)
- Pale or purple fingers or toes from cold or stress
- Sensitivity to the sun
- Low blood count
- Depression, trouble thinking, and/or memory problems.
Other signs are mouth sores, unexplained seizures (convulsions), “seeing things” (hallucinations), repeated miscarriages, and unexplained kidney problems.
Exams and Tests
There is no single test to diagnose lupus. It may take months or years for a doctor to diagnose lupus. Your doctor may use many tools to make a diagnosis: