Sickle cell anemia Health Article

Definition

Sickle cell anemia is a disease passed down through families in which red blood cells form an abnormal crescent shape. (Red blood cells are normally shaped like a disc.)

Alternative Names

Anemia - sickle cell; Hemoglobin SS disease (Hb SS); Sickle cell disease

Causes, incidence, and risk factors

Hemoglobin is a protein inside red blood cells that carries oxygen. Sickle cell anemia is caused by an abnormal type of hemoglobin called hemoglobin S. Hemoglobin S distorts the shape of red blood cells, especially when there is low oxygen.

The distorted red blood cells are shaped like crescents or sickles. These fragile, sickle-shaped cells deliver less oxygen to the body's tissues. They also can clog more easily in small blood vessels, and break into pieces that disrupt blood flow.

Sickle cell anemia is inherited from both parents. 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.

Someone who inherits the hemoglobin S gene from one parent and normal hemoglobin (A) from the other parent will have sickle cell trait. People with sickle cell trait do not have the symptoms of true sickle cell anemia.

Symptoms

Symptoms usually don't occur until after age 4 months.

Almost all patients with sickle cell anemia have painful episodes (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
• Jaundice
• Paleness
• Rapid heart rate
• Ulcers on the lower legs (in adolescents and adults)

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