Sickle Cell Anemia

Sickle Cell Anemia

Alternate Names

  • sickle cell trait
  • Sickle cell anemia

Definition

Sickle cell anemia is an inherited blood disease. It causes serious health problems among African Americans or individuals of African descent.

What is going on in the body?

Hemoglobin is the key molecule in the blood that carries oxygen to all parts of the body. A change in a certain gene causes a change in the structure of hemoglobin. Persons with normal hemoglobin have a genetic coding of AA. Persons with sickle cell trait have a genetic coding of AS. (The "S" refers to the sickle cell gene.)
Eight percent of African Americans are carriers of the sickle cell gene, and thus are said to have sickle cell trait. Most people with sickle cell trait are completely healthy and lead normal lives, though a variety of symptoms can occur with heavy exercise or exposure to high altitudes.
Persons with the genetic coding SS have inherited one "S" gene from each parent and therefore, totally lacking the "A" gene for normal hemoglobin, they develop sickle cell anemia. It affects approximately 15 out of every 1000 African Americans. In sickle cell anemia the abnormal hemoglobin molecule forces the red blood cells to change shape from a rounded disk to a crescent or "sickle" shape.
These abnormal red blood cells are more rigid and are more likely to clump together. They are also more likely to stick to the walls of blood vessels and can even block the blood vessels themselves. These changes also mean that the hemoglobin molecule fails to carry oxygen as well as it should.

Risks

What are the causes and risks of the disease?

Sickle cell anemia is caused by a change in a gene that changes the structure of the hemoglobin molecule.
Sickle cell anemia is a long-term disease that causes a number of health risks. Individuals have a severe anemia that puts extra strain on the heart, which can lead to heart enlargement. These individuals have a reduced life expectancy. They are at increased risk of the following:
  • infection
  • blood clots in the legs or lungs
  • kidney failure
  • gallstones
  • seizures
  • strokes
  • coma
Pregnant women with sickle cell anemia are likely to have kidney infections, bleeding, premature infants, and fetal death.

Prevention

What can be done to prevent the disease?

For an individual with the SS genetic coding for hemoglobin, there is no effective prevention of sickle cell anemia. However, individuals with sickle cell trait (AS coding) can benefit from genetic counseling. If two parents are both carriers of the sickle cell trait, they have a 25% chance of having a child with sickle cell anemia.

Diagnosed

How is the disease diagnosed?

The disease is diagnosed through a combination of medical history, physical examination, and laboratory testing. A vital laboratory test is the peripheral blood smear. This test will show the characteristic sickle shape of some red blood cells. There is usually a very low red blood cell count, due to the breakdown of the red blood cells.
White blood cells counts are often higher than normal. Liver function tests may be abnormal. A specialized test called hemoglobin electrophoresis will confirm the diagnosis. X-rays may show abnormal changes in bone, especially of the spine and hip.

Long Term Effects

What are the long-term effects of the disease?

Many individuals with sickle cell anemia develop serious, long-term medical problems. These include:
  • severe anemia , which is a shortage of red blood cells
  • decrease in kidney function
  • heart attacks
  • avascular necrosis, a type of deterioration of the hip joint
  • stroke
  • seizures
  • brain hemorrhages
  • blindness
  • leg ulcers that are difficult to heal
The repeated episodes of severe pain often reduce the quality of daily life. Narcotic pain relievers are often used to treat these painful crises. This can lead to a risk of becoming dependent on these drugs.

Other Risks

What are the risks to others?

Sickle cell anemia is passed from parent to child. It is not contagious.

Treatments

What are the treatments for the disease?

Sickle cell anemia is a lifelong chronic disease with no cure. Because sickle cell anemia causes so many health problems, persons with the disease need to establish a good relationship with a healthcare professional. Some treatments for sickle cell anemia help to prevent other complications.

In some patients who frequently have to be hospitalized or are very anemic even without a crisis, hydroxyurea may be considered. This medication helps prevent the red cells from sickling. Long-term use of hydroxyurea, however, may increase the risk for leukemia and should be prescribed in consultation with a hematologist.
  • The pneumococcal vaccine helps prevent serious infections by the Pneumococcus bacterium.
  • Preventive antibiotics before a dental procedure are recommended.
  • For persons who live where malaria is present, preventive medication is recommended.
  • A daily folic acid supplement is recommended to prevent a deficiency of this nutrient.
  • An annual eye examination by an eye care professional can detect eye problems early.
  • Because of the increased risk of infection, it is necessary to have any fever, chills, or other signs of infection checked out by a healthcare professional promptly. Infections are treated with antibiotics.
  • Fluids are needed to prevent or correct dehydration.
  • Individuals can develop blood in the urine, called hematuria, that lasts days to weeks.
Plenty of fluid is essential to maintain urine flow and to prevent blood clots. If blood clots form in the legs or lungs, blood thinners, or anticoagulants, are used.
  • Some men develop priapism, a painful and prolonged erection of the penis. Repeated episodes can lead to impotence, which can be helped with a penile prosthesis.

Side Effects

What are the side effects of the treatments?

General supportive care, such as pain control and fluids, has no specific side effects.
  • Blood thinners used to treat blood clots can cause excessive bleeding.
  • Antibiotics used to treat infection may also have side effects. These include rashes, gastrointestinal symptoms, and even anaphylaxis, a life-threatening allergic reaction.
  • Chronic use of narcotics to relieve pain can sometimes lead to dependence and addiction.

After Treatment

What happens after treatment for the disease?

After treatment of a specific problem, such as a painful crisis or an infection, the person may have periods of time with few symptoms.

Monitor

How is the disease monitored?

There is no specific test for monitoring sickle cell anemia. A person's symptoms and certain lab tests are the best ways to monitor the disease.

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