Sickle cell anemia is an inherited blood disorder characterized by both a deficiency of healthy red blood cells (anemia) and painful episodes called sickle cell crises.
The disorder is caused by a mutation in the gene that tells the body to make hemoglobin, a protein found in red blood cells that binds to oxygen in the lungs and carries it to tissues throughout the body.
As a result of the mutation, the body produces a defective form of hemoglobin called hemoglobin S, which causes red blood cells to sickle, or develop a crescent shape.
To have sickle cell anemia, a person must inherit two sickle hemoglobin genes, one from each parent.
A person who inherits a sickle hemoglobin gene from one parent and a normal hemoglobin gene from the other parent is said to have sickle trait.
People with sickle trait generally don't have symptoms related to it, but they are at risk of developing certain medical problems, and they can pass the sickle hemoglobin gene to their children.
Normal red blood cells are disc-shaped and flexible, and they slide easily through the circulatory system.
Sickle hemoglobin causes red blood cells to develop a sickle, or crescent, shape.
Sickle cells are stiff and sticky and tend to block blood flow in the vessels of the limbs and organs, causing pain and raising the risk for infection.
Sickle cells also have a shorter life span than normal red blood cells, leading to an overall shortage of red blood cells and, consequently, anemia.
Sickle cell anemia affects millions of people around the world.
It's most common in people of African, Middle Eastern, Mediterranean, Central and South American, and Asian Indian origin or descent.
The continent of Africa is particularly hard hit, with sickle cell anemia affecting up to 3 percent of all births in some parts of sub-Saharan Africa, according to research published in the American Journal of Preventive Medicine.
In the United States, an estimated 70,000100,000 people have sickle cell anemia, according to the National Heart, Lung and Blood Institute.
African-Americans are affected most often: 1 out of every 500 African-American newborns has sickle cell anemia.
The prevalence of the gene mutation that causes sickle cell is higher in areas of the world where malaria is found.
Researchers have found that having sickle cell trait offers some survival advantage against malaria.
Symptoms of sickle cell anemia typically start after the fifth or sixth month of life. Common signs and symptoms include:
Episodes of pain, called sickle cell crises, occur when sickled red blood cells block blood flow to the limbs and organs.
Treatment of sickle cell anemia includes:
As little as 40 years ago, almost 15 percent of children born with sickle cell anemia died before age two, and many more died as teens, according to the National Heart, Lung and Blood Institute.
Now, because of improved treatments and care, people who have sickle cell anemia are living into their 40s, 50s, or longer.
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The hallmark symptom of sickle cell anemia is pain, particularly episodes of sudden pain, sometimes called sickle cell crises.
Fatigue is another common symptom, which results from anemia, or a deficiency of healthy red blood cells.
However, sickle cell symptoms vary from person to person: Many people have chronic, low-level pain, with or without occasional sickle cell crises, while others have multiple crises each year.
The degree of anemia also varies among individuals.
Infants with sickle cell anemia generally dont develop symptoms until after the fifth or sixth month of life, when their level of fetal hemoglobin, which protects red blood cells from sickling, declines.
Sickle cell anemia is diagnosed with either a blood test that measures the presence and relative amount of hemoglobin S, the defective form of hemoglobin that underlies the disorder, or with a genetic test.
In the United States, all states and the District of Columbia mandate testing for sickle cell anemia as part of their newborn screening programs.
However, this requirement is relatively recent, and other countries do not mandate screening, so many adults have not been tested to determine their sickle cell status.
Testing for the sickle hemoglobin gene can also be done before birth, as early as 10 weeks into pregnancy.
Episodes of acute pain often referred to as sickle cell crises are caused by sickled red blood cells blocking blood flow to the limbs or organs.
Some crises can be treated at home, with rest, pain relievers, and hydration, while others require hospitalization and such measures as intravenous fluids, oxygen therapy, and strong pain medication.
The pain of a sickle cell crisis starts suddenly and may last for hours or continue for days or even weeks. It can occur anywhere in the body but often is felt in the bones, joints, chest, back, or abdomen.
Pain may be accompanied by tenderness, swelling, and redness over the area of the blocked blood flow.
In young children, blockages frequently occur in the small bones of the hands and feet, causing acute, painful swelling.
Painful crises are the most common reason for emergency room visits and hospital stays for people with sickle cell anemia.
The anemia associated with sickle cell anemia is called hemolytic anemia, because it is caused by the destruction of sickled red blood cells.
Symptoms of anemia can include:
Severe anemia can cause:
A hematologist (a physician with special training in blood disorders) can identify the best way to manage the anemia associated with sickle cell anemia.
Medical care should be sought immediately if any of the following develop:
These symptoms may mean that a person is experiencing a serious, even life-threatening, complication of sickle cell anemia.
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Treatment of sickle cell anemia includes taking measures to treat anemia, prevent sickle cell crises and other complications, and treat any crises or complications that occur.
Children with sickle cell anemia are at high risk of infection, so much of their routine care is aimed at preventing infection by the following:
The drug hydroxyurea is approved for use in adults with sickle cell anemia and is sometimes used in children too.
Hydroxyurea causes the body to produce fetal hemoglobin, a type of hemoglobin that is normally produced only before and shortly after birth.
The presence of fetal hemoglobin lengthens the life span of red blood cells and makes them less likely to sickle.
It takes several months for hydroxyurea to start having any benefit.
People taking hydroxyurea should have their blood checked monthly to assess the effect of the drug and to help determine the correct dose.
Possible short-term side effects of hydroxyurea include gastrointestinal complaints and, rarely, darkening of the skin and nails.
Little is known about the long-term side effects of hydroxyurea.
When treating pain associated with sickle cell anemia at home, the following can help:
In a hospital, sickle cell crises are generally treated with:
Blood transfusions may be needed in some situations, such as:
Some people need blood transfusions only occasionally, while others need them regularly.
Blood transfusions have their own complications, including transfusion-induced iron overload.
Because the body does not have a way to get rid of iron received from blood transfusions, excess iron can build up in and damage vital organs.
Iron overload is prevented with a class of medications called iron chelators, drugs that attach to iron in the body so that it can be excreted in feces.
Blood and bone marrow stem cell transplants may be used to treat sickle cell anemia and may offer a cure for a small number of people.
They are performed mainly in children with sickle cell anemia, although early studies suggest they may be feasible in adults as well.
Stem cells are found in bone marrow and, in smaller quantities, in blood and in the umbilical cord. Stem cells can develop into red blood cells, white blood cells, and platelets.
The stem cells used for a transplant must come from a closely matched donor usually a family member who does not have sickle cell anemia.
Maintaining a healthy lifestyle with sickle cell anemia can help with symptoms and includes:
People with sickle cell anemia can also help to prevent sickle cell crises by following these precautions:
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Sickle cell anemia can cause a broad array of complications, some which are medical emergencies requiring immediate treatment.
If you or your child has sickle cell anemia, talk to your doctor about the signs and symptoms that may point to a serious problem.
Acute chest syndrome is similar to pneumonia, in which the lungs fill up with fluid.
Symptoms include fever, rapid breathing, chest pain, coughing, and shortness of breath.
There are a few possible causes of acute chest syndrome, including:
Acute chest syndrome is the leading cause of death from sickle cell anemia in the United States, according to the American College of Emergency Physicians.
Delayed growth and delayed puberty are common among children with sickle cell anemia.
Adults with sickle cell anemia often tend to be smaller than average.
Sickle cells can plug up the tiny blood vessels that supply your eyes, damaging the retina, the light-sensitive layer of tissue at the back of the inner eye, and potentially causing blindness.
The breakdown of red blood cells produces a substance called bilirubin, and a high level of bilirubin in your body can lead to gallstones hard masses that form in the gall bladder.
Gallstones can cause pressure, pain, and nausea if they get stuck in the common bile duct.
People with sickle cell anemia often have a high bilirubin level because sickled red blood cells are broken down after 10 to 20 days versus 120 days for normal red blood cells.
In young children, blockages in blood flow frequently occur in the small bones of the hands and feet, causing acute, painful swelling.
People with sickle cell anemia have a higher-than-normal risk for infection for several reasons, including:
Any infection in a child with sickle cell anemia is considered an emergency.
Jaundice is a yellowish discoloration of the skin and the whites of the eyes. Jaundice results from the excess of bilirubin caused by the rapid destruction of sickle cells.
Acute multi-organ failure is a rare but life-threatening complication that may occur during a sickle cell crisis.
Multiple organ failure is treated with blood transfusion therapy.
If sickle cells block the blood vessels in the penis, the result can be priapism a painful, long-lasting erection.
Priapism can cause serious damage to the penis and result in impotence.
Men experiencing priapism should seek medical attention immediately.
Pulmonary hypertension is high blood pressure in the arteries that carry blood to the lungs.
It occurs in about 30 percent of adults with sickle cell anemia, according to the National Library of Medicine, and it can be fatal.
Symptoms of pulmonary hypertension include shortness of breath with everyday activities, fatigue, shortness of breath, dizziness, and fainting spells.
Splenic sequestration is an acute condition in which large amounts of blood build up in the spleen, causing the spleen to enlarge, sometimes enormously.
It is seen most commonly in children and is potentially life threatening.
A stroke can occur if sickle cells block blood flow to an area of the brain.
Strokes usually cause such symptoms as:
However, it's also possible to have a "silent stroke" that doesn't cause the usual symptoms but can have lasting effects on the brain.
Long-term effects of stroke can include:
According to the Internet Stroke Center, stroke occurs in 17 to 24 percent of children with sickle cell anemia, most often between the ages of 3 and 10.
Adults with sickle cell anemia are also at risk for stroke.
Children at risk of stroke can be monitored with a type of imaging study called transcranial Doppler ultrasound.
If abnormalities are found, the doctor may recommend a blood transfusion.
Leg ulcers non-healing or slowly healing wounds are a fairly common complication that can be disabling.
They typically occur first around the ankles and can cause severe pain.
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People with sickle cell anemia inherit two genes for sickle hemoglobin one from each parent.
People with sickle cell trait inherit one sickle hemoglobin gene from one parent and one normal gene from the other parent.
According to the American Society of Hematology, between 1 million and 3 million Americans have sickle cell trait, and more than 100 million people have it worldwide.
Like sickle cell anemia, sickle cell trait is most common among people of African, Middle Eastern, Mediterranean, Central and South American, and Asian Indian origin or descent.
Having sickle cell trait has been found to offer some survival advantage against malaria.
Not surprisingly, sickle cell trait is most prevalent in areas of the world affected by malaria.
In the United States sickle cell trait is most common among African-Americans: About 1 in 12 African-Americans has it. Among Hispanic Americans, 1 in 100 has it.
While most people with sickle cell trait can safely participate in sports and exercise, some athletes with the trait have experienced illness or have even died as a consequence of strenuous exertion.
Exercising too intensively can lead to exertional rhabdomyolysis, a condition in which skeletal muscle rapidly breaks down.
Signs and symptoms of exertional rhabdomyolysis include fatigue, muscle pain, and darkened urine.
In response to a lawsuit following the death of a college football player with undiagnosed sickle cell trait in 2006, the National Collegiate Athletic Association (NCAA) now requires all athletes at Division I and II schools to be tested for sickle cell trait or to sign a written release declining testing before competing.
Preventive measures to avoid overexertion and problems associated with exercising in hot or humid conditions include:
Although sickle cell trait is generally considered a benign, or harmless, condition, it has been associated with a variety of medical conditions, including:
People with sickle cell trait can pass the sickle gene on to their children.
If both parents have sickle cell trait, there's a chance their children will have sickle cell anemia.
If one person in a family is diagnosed with sickle cell anemia, it's often advised that the whole family be tested so that each member knows his sickle cell status.
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Source: http://www.everydayhealth.com
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