What is sickle cell anemia?

Sickle cell anemia (sickle cell disease) is a disorder of the blood caused by an inherited abnormal hemoglobin (an oxygen-carrying protein within the red blood cells). The abnormal hemoglobin causes distorted (sickled) red blood cells. The sickled red blood cells are fragile and prone to rupture. When the number of red blood cells decreases from rupture (hemolysis), anemia is the result. This condition is referred to as sickle cell anemia. The irregular sickled cells can also block blood vessels causing tissue and organ damage and pain.

Sickle cell anemia is one of the most common inherited blood anemias. The disease primarily affects Africans and African Americans. It is estimated that in the United States, some 50,000 African Americans are afflicted with the most severe form of sickle cell anemia. Overall, current estimates are that one in 1,875 U.S. African American is affected with sickle cell anemia.

Causes, incidence, and risk factors?
Sickle cell anemia is caused by an abnormal type of hemoglobin called hemoglobin S. Hemoglobin is a protein inside red blood cells that carries oxygen. Hemoglobin S changes the shape of red blood cells, especially when the cells are exposed to low oxygen levels. The red blood cells become shaped like crescents or sickles.
The fragile, sickle-shaped cells deliver less oxygen to the body's tissues. They can also get stuck more easily in small blood vessels, and break into pieces that interupt healthy blood flow.
Sickle cell anemia is inherited from both parents. If you inherit the hemoglobin S gene from one parent and normal hemoglobin (A) from your other parent, you will have sickle cell trait. People with sickle cell trait do not have the symptoms of sickle cell anemia.
Sickle cell disease is much more common in people of African and Mediterranean descent. It is also seen in people from South and Central America, the Caribbean, and the Middle East.

what are the Symptoms?
Symptoms usually don't occur until after age 4 months.
Almost all patients with sickle cell anemia have painful episodes (called crises), which can last from hours to days. These crises can affect the bones of the back, the long bones, and the chest.
Some patients have one episode every few years. Others have many episodes per year. The crises can be severe enough to require a hospital stay.
Common symptoms include:

*Attacks of abdominal pain
*Bone pain
*Breathlessness
*Delayed growth and puberty
*Fatigue
*Fever
*Paleness
*Rapid heart rate
*Ulcers on the lower legs (in adolescents and adults)
*Yellowing of the eyes and skin (jaundice)

Other symptoms include:
*Chest pain
*Excessive thirst
*Frequent urination
*Painful and prolonged erection (priapism - occurs in 10 - 40% of men with the disease)
*Poor eyesight/blindness
*Strokes
*Skin ulcers

what are the Signs and tests?
Tests commonly performed to diagnose and monitor patients with sickle cell anemia include:
*Complete blood count (CBC)
* Hemoglobin electrophoresis
* Sickle cell test
Other tests may include:
* Bilirubin
* Blood oxygen
*CT scan or MRI
*Peripheral smear
* Serum creatinine
*Serum hemoglobin
* Serum potassium
* Urinary casts or blood in the urine
*White blood cell count

How is sickle cell anemia inherited?
Sickle cell anemia is inherited as an autosomal (meaning that the gene is not linked to a sex chromosome) recessive condition whereas sickle cell trait is inherited as an autosomal dominant trait. This means that the gene can be passed on from a parent carrying it to male and female children. In order for sickle cell anemia to occur, a sickle cell gene must be inherited from both the mother and the father, so that the child has two sickle cell genes.

The inheritance of just one sickle gene is called sickle cell trait or the "carrier" state. Sickle cell trait does not cause sickle cell anemia. Persons with sickle cell trait usually do not have many symptoms of disease and have normal hospitalization rates and life expectancies. Sickle cell trait is present in some two million blacks in the United States (8% of the U.S. black population at birth). When two carriers of sickle cell trait mate, their offspring have a one in four chance of having sickle cell anemia. (In some parts of Africa, one in five persons is a carrier for sickle cell trait.)

How Is Sickle Cell Anemia Treated?
Sickle cell anemia has no widely available cure. However, treatments can help relieve symptoms and treat complications. The goals of treating sickle cell anemia are to relieve pain; prevent infections, eye damage, and strokes; and control complications (if they occur).

Bone marrow transplants may offer a cure in a small number of sickle cell anemia cases. Researchers continue to look for new treatments for the disease. These include gene therapy and improved bone marrow transplants.

what are the Complications?
Acute chest syndrome
Anemia
Blindness/vision impairment
Brain and nervous system (neurologic) symptoms and stroke
Death
Disease of many body systems (kidney, liver, lung)
Drug (narcotic) abuse
Erectile dysfunction (as a result of priapism)
Gallstones
Hemolytic crisis
Infection, including pneumonia, gallbladder inflammation (cholecystitis), bone infection (osteomyelitis), and urinary tract infection
Joint destruction
Leg sores (ulcers)
Loss of function in the spleen
Parvovirus B19 infection, leading to low red blood cell production (aplastic crisis)
Splenic sequestration syndrome
Tissue death in the kidney.
Painful crises
Any symptoms of infection (fever, body aches, headache, fatigue

what are the Prevention measures?
Sickle cell anemia can only occur when two people who carry sickle cell trait have a child together. Genetic counseling is recommended for all carriers of sickle cell trait. About 1 in 12 African Americans has sickle cell trait.
It is possible to diagnose sickle cell anemia during pregnancy.
If you have sickle cell anemia, you can prevent the change in red blood cell shape by:
* Getting enough fluids
* Getting enough oxygen
* Quickly treating infections
Have a physical exam every 3 - 6 months to make sure that you are getting enough nutrition and activity, and that you are receiving the proper vaccinations. Regular eye exams are recommended.

PREVENTING CRISES
It is important to maintain good oxygen levels and to prevent dehydration. The following steps can help prevent a sickle cell crisis:
*Avoid strenuous activities, stress, smoking, high-altitudes, no pressurized flights, and other events that reduce your oxygen level
*Always have plenty of fluids with you
*Avoid too much sun exposure
Consider having the child with sickle cell anemia wear a Medic Alert bracelet. Share the above information with teachers and other caretakers, when necessary.

PREVENTING INFECTIONS
*People with sickle cell anemia need to keep their immunizations up to date to prevent illness.
*Some patients may receive antibiotics to prevent infections.
 

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