Dr. X
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عدد الرسائل : 287
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المحافظة : فلسطيني
الهوايات : الفروسية,الرماية والسباحة
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تاريخ التسجيل : 19/10/2008
 | موضوع: Sickle cell anemia  الإثنين نوفمبر 17, 2008 2:07 pm | |
| Sickle cell anemia is an inherited blood disorder that mostly affects people of African ancestry, but also occurs in other ethnic groups, including people who are of Mediterranean and Middle Eastern descent.
More than 70,000 Americans have sickle cell anemia. And about 2 million Americans — 1 in 12 African Americans — have sickle cell trait, which means they carry a single gene for the disease, but do not have the disease itself.
What Is Sickle Cell Anemia?
Sickle cell anemia is a blood disorder that affects hemoglobin (pronounced: hee-muh-glow-bin), the protein found in red blood cells (RBCs) that helps carry oxygen throughout the body.
Sickle cell anemia occurs when a person inherits two abnormal genes (one from each parent) that cause their RBCs to change shape. Instead of being flexible and disc-shaped, these cells are more stiff and curved in the shape of the old farm tool known as a sickle — that's where the disease gets its name. The shape is similar to a crescent moon.
Red blood cells with normal hemoglobin (hemoglobin A, or HbA) move easily through the bloodstream, delivering oxygen to all of the cells of the body. Normal RBCs are shaped like discs or doughnuts with the centers partially "scooped out" and are soft and flexible. They can easily "squeeze" through even very small blood vessels.
Sickle cell anemia occurs because an abnormal form of hemoglobin (HbS) is produced. HbS molecules tend to clump together, making red blood cells sticky, stiff, and more fragile, and causing them to form into a curved, sickle shape.
RBCs containing HbS can go back and forth between being shaped normally and being sickle shaped until they eventually become sickle shaped permanently. Instead of moving through the bloodstream easily, these sickle cells can clog blood vessels and deprive the body's tissues and organs of the oxygen they need to stay healthy.
Unlike normal RBCs that last about 4 months in the bloodstream, fragile sickle cells break down after only about 10 to 20 days, which usually causes anemia. Anemia (pronounced: uh-nee-mee-uh) is what happens when the body's number of red blood cells (or amount of hemoglobin) falls below normal. People who are anemic often feel weak, tire more easily, and may appear "run down."
People with sickle cell anemia can also experience complications from impaired blood circulation and infection-fighting problems. These include a higher risk of certain infections and stroke as well as a condition called acute chest syndrome, which is caused by inflammation or trapped RBCs in the lungs.
Sickle cell anemia is not contagious, so you can't catch it from someone else or pass it to another person like a cold or an infection. People with sickle cell anemia have inherited two sickle cell genes, one from each parent. A child who has inherited the sickle cell gene from only one parent will not develop the disease, but will have sickle cell trait. People who have sickle cell trait don't have sickle cell anemia or symptoms of the disease, but they can pass the sickle cell gene on to their own children.
Because people with sickle cell trait don't have the disease, they may never discover that they carry the gene. That's why it's recommended that teens who are unsure of their sickle cell status ask their doctors about testing. The National Institutes of Health (NIH) recommends that all newborns be screened for sickle cell disease, and testing at birth is now required in almost every state. This helps infants with sickle cell anemia get the care and treatment they need right away.
Signs and Symptoms
Teens with sickle cell anemia may develop jaundice (pronounced: jon-dis), a condition that results from the high rate of red blood cell breakdown. Jaundice can cause the skin and the whites of a person's eyes to develop a yellowish tint.
People with sickle cell anemia also may have bouts of severe pain in the chest, stomach, arms, legs, or other parts of the body. This is caused by sickle cells blocking blood flow through the blood vessels in those areas. Feeling tired and having trouble fighting infections are also common among teens with sickle cell anemia, and they may grow more slowly and reach puberty later than other teens.
Periods of pain are commonly referred to as pain crises, which vary in their severity, how often they happen, and how long they last. Whereas one person may have only one sickle cell pain crisis a year, another may experience them more often. Crises may be brief, or may last hours, days, or even weeks. Symptoms can develop in any body organ or tissue and include aching arms, legs, hips, and shoulders. When people with sickle cell disease get acute chest syndrome, they may have severe chest and abdominal pain, fever, cough, and trouble breathing.
What Can Doctors Do?
To diagnose sickle cell anemia, doctors use a special blood test called hemoglobin electrophoresis (pronounced:eh-lek-tro-fuh-ree-sis) to look for HbS in a person's blood.
There is no cure for sickle cell anemia, and it is possible for some people to be ill enough to die from the disease (although most young people with sickle cell anemia don't die). Doctors can provide treatments that help prevent complications from the disease, though. Folic acid, a vitamin that helps the body produce new red blood cells, is often prescribed for teens with sickle cell anemia. Pain medications help relieve the symptoms of crises. And kids and teens who have sickle cell disease should take penicillin or other antibiotics to help prevent infections.
Some crises can be managed at home with pain medicines, rest, and extra fluids. But if a crisis is especially intense, a teen may need to go to the hospital for intravenous (IV) fluids and stronger pain medications. People with sickle cell anemia may also use oxygen to help ease symptoms during a crisis or an episode of acute chest syndrome.
Teens with sickle cell anemia may need to get transfusions of healthy red blood cells to help carry oxygen to the tissues of their bodies more effectively, and some may need many transfusions on a regular basis.
Scientists are constantly researching ways to help people with sickle cell anemia. Several new treatments, such as the drug hydroxyurea, have helped reduce painful crises and episodes of acute chest syndrome in adults with the condition. These drugs have also decreased the need for hospitalization. Scientists are also testing these and other drugs to see if they work for kids and teens. In rare cases, people with severe sickle cell anemia may be given a bone marrow transplant to help them produce healthy hemoglobin and normal RBCs.
Scientists are also studying gene therapy as a treatment for sickle cell anemia. One day, doctors may be able to stop the disease by changing or replacing the abnormal gene that causes it.
What Can You Do to Stay Well?
With the right precautions, teens with sickle cell disease can do most of the stuff other teens do. To stay as healthy as possible, take these steps:
- Eat a balanced, healthy diet.
- Take vitamins, including folic acid supplements, as prescribed.
- Drink plenty of fluids to prevent dehydration.
- Avoid extreme cold or heat.
- Exercise regularly, but in moderation. Exercise is important for staying healthy, but overdoing it can trigger a crisis in some people, particularly if they become dehydrated, overheated, or exhausted.
- Get plenty of rest.
- Avoid alcohol, drugs, and smoking, which can aggravate sickle cell disease and its symptoms. Some people with sickle cell disease are prone to lung problems, so smoking is particularly risky and must be avoided.
- Avoid places low in oxygen. (For example, it's not a good idea to go hiking at high altitudes or spend lots of time swimming under water.)
- Prevent serious infections by contacting your doctor as soon as illness symptoms start. Be sure to get any immunizations (such as pneumonia and flu vaccines) that the doctor recommends, and always call your doctor if you have a high fever (over 101° Fahrenheit).
- Learn as much as you can about the disease and see your doctor regularly to help prevent complications.
Teens with sickle cell disease may need to put some limits on their lives, but with the help of doctors, friends, and family, they can manage the condition and live their lives to the fullest. | |
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