Chantelle was having a rough morning. Her hands were so stiff that she could barely dial the combination on her locker. Then she couldn't move her fingers well enough to play her clarinet. It seemed that ever since marching band practice had started in the early summer, her hands and feet felt sore in the mornings. She was also tired all the time, and no matter how much she rested, she still felt sleepy and achy all over.

Chantelle told her doctor about her achy hands and feet and how she felt tired all the time. The doctor sent her for blood tests. A few days later, the doctor called and told Chantelle's dad that she might have lupus.

What Is Lupus?

Lupus (pronounced: loo-pus) is a disease that involves the immune system and affects about 1.5 million Americans; nearly 90% of those diagnosed with the disease are female. Normally, a person's immune system works by producing immunity cells and antibodies, special substances that fight germs and infections. But when a person has lupus, his or her immune system goes into overdrive and can't tell the difference between some of the body's normal, healthy cells and germs that can cause infection. So the immune system responds by making autoantibodies that attack the body's normal cells.

There are three types of lupus:

Systemic Lupus Erythematosus (pronounced: er-uh-thee-muh-toe-sus)
Also called SLE, this is the type of lupus that most people mean when they talk about the disease. It was given its name by a 19th century French doctor who thought that the facial rash of some people with lupus looked like the bite or scratch of a wolf ("lupus" is Latin for wolf and "erythematosus" is Latin for red).

SLE is the most serious form of lupus. Like Chantelle, about 15% of the people who have SLE first start to feel sick when they are teens. SLE can affect the skin, joints, and tendons. It may also affect organs like the brain, heart, lungs, and kidneys.

Discoid (pronounced: dis-koyd) Lupus

This type of lupus is a skin disease that causes a rash on the face, neck, scalp, and ears. It is a much more rare form of lupus than SLE, although about 10% of people with discoid lupus will develop a mild form of SLE. It doesn't affect other body organs the way that SLE can. The rash of discoid lupus can cause scarring, though.

Drug-Induced Lupus

This type of lupus is caused by a reaction to certain kinds of medicines. For example, some types of antiseizure medicines and acne medicines can cause this kind of lupus in teens. Drug-induced lupus is similar to SLE in the ways it affects the body, but once a person stops taking the medicine, the symptoms usually go away.

What Causes Lupus?

No one really knows what causes lupus. Researchers think that some people may be more likely to get it due to things that are out of their control, like:

• gender. Many more women get lupus than men; there are 10 women to every one man with lupus.
• estrogen. This female hormone may be a factor in lupus - almost all women who get lupus are of childbearing age.
• race/ethnicity. Lupus occurs more often in African-American, Asian-American, Latin-American, and Native-American women than in non-Hispanic Caucasian women.
• family history/genetics. About 10% of people with lupus have a family member with lupus.
• major stress or infection. If people have the genetic tendency to get lupus, extreme stress or an infection may trigger the disease - but the blueprint for lupus has to already be there. One thing researchers know about lupus is that it is not contagious. You can't catch any of the three types of lupus from another person. And although lupus involves the immune system, it is not the same as other diseases that involve the immune system, like AIDS.

What Are the Symptoms of Lupus and How Is It Diagnosed?

Lupus can be hard to diagnose because its symptoms can vary from one person to the next. The symptoms can also make lupus look like certain other diseases. For example, like Chantelle, people with lupus may feel weak and fatigued. They may have muscle aches, loss of appetite, swollen glands, and hair loss. Sometimes they have abdominal pain, nausea, diarrhea, and vomiting.

If a doctor thinks that a patient might have lupus, the doctor may perform certain blood tests. If lupus is suspected, the doctor will probably send the person to a rheumatologist (pronounced: roo-muh-tah-luh-jist). Rheumatologists are doctors who have special training in diagnosing and treating autoimmune diseases like lupus.

Because signs and symptoms of SLE can be so varied, there are 11 specific signs a rheumatologist will also look for:

• malar rash. A malar (pronounced: may-lur) rash appears across the nose and cheeks in the shape of a butterfly.
• discoid rash. This rash features round, red, scaly patches that can appear on the face, arms, scalp, or ears.
• photosensitivity. This means sensitivity to ultraviolet rays, like the ones that come from the sun or from fluorescent lights. Most people with SLE are photosensitive and find that the sun worsens their lupus.
• ulcers in the nose or mouth. These usually don't hurt and many people with SLE don't even know they are there.
• arthritis. This makes joints hurt, especially in hands and feet. Unlike the kind of arthritis that older people sometimes get, this arthritis doesn't damage the bones. Most people with SLE have some degree of arthritis.
• serositis (pronounced: sir-o-syte-us). This is the collection of fluid near the linings covering the heart, lungs, or abdomen.
• kidney problems. These can be mild or severe. Most people with SLE will have kidney problems, but only about half of them will have permanent kidney damage.
• neurologic problems. This refers to problems with the brain and nervous system, like seizures.
• blood problems. SLE can cause a lower than normal number of red blood cells (anemia), white blood cells, or platelets.
• immune system problems. Blood tests may show that the immune system isn't functioning properly.
• positive ANA test. This is a blood test that shows a certain type of antibody. About 95% of people with SLE have a positive ANA test.

If a person has four or more of these signs or symptoms, it is likely that he or she has SLE. Most patients don't develop all 11 of them.