Sickle cell disease is a group of inherited blood disorders that causes a structural abnormality in most or all of the hemoglobin in the red blood cells (RBCs). Sickle cell anemia is the most common of the sickle cell diseases and most frequently occurs in people of African or Mediterranean descent. The abnormal hemoglobin of sickle cell disease is called hemoglobin S. It causes the RBCs to be crescent or sickle shaped instead of the normal disc shape. Sickled RBCs are problematic for two reasons. First, sickled RBCs do not live as long in the circulation as normal RBCs. Hence, people with sickle cell disease are chronically anemic--that is, they have too few circulating RBCs. The second problem is sickled RBCs tend to get stuck in the smallest blood vessels of the body, collectively called the microcirculation. When sickled cells lodge in the microcirculation, blood flow is obstructed. The tissues normally supplied by the blocked blood vessels are starved of oxygen and nutrients. These two problems are directly or indirectly responsible for virtually all the symptoms and complications of sickle cell disease. The symptoms associated with sickle cell anemia also occur with other sickle cell diseases, though they are typically less frequent and severe.
Pain Crises
People with sickle cell anemia are subject to episodes of severe pain called pain crises. The bones and joints, chest and abdomen are most commonly affected. Sickled RBCs obstruct the microcirculation, causing small areas of tissue damage or death due to lack of oxygen. This gives rise to severe pain.
Hand-Foot Syndrome
Sickle cell anemia can cause a condition called hand-foot syndrome, which is characterized by pain and swelling of the hands and feet. Fever may also occur. Sickled RBCs blocking the microcirculation of the extremities cause the syndrome.
Anemia Symptoms
Anemia causes persistent fatigue, a feeling of tiredness and lack of energy. Other symptoms related to the anemia of sickle cell disease include paleness, cold hands and feet, shortness of breath, poor exercise tolerance, weakness and headache.
Skin Ulcers
People with sickle cell anemia often have ulcers on the lower legs and ankles. The sores typically begin around age 10 and occur throughout adulthood. They are more common in men than in women. The ulcers can persist for years and sometimes recur after healing.
Vision Problems
Blockages in the blood vessels that supply the eyes can damage the retina--the part of the eye that perceives visual input and communicates what is seen to the brain. People with sickle cell anemia often have poor eyesight and are at risk for blindness because of the effects of sickled RBCs on the eyes' blood supply.
Episodic Breathing Problems
Sickle cell anemia can cause a condition called acute chest syndrome, which is characterized by sudden chest pain, fever, cough and shortness of breath. Fluid accumulates in one or both lungs partially blocking the normal flow of oxygen from the lungs into the circulation. Bacterial pneumonia frequently complicates acute chest syndrome.
Delayed Growth and Puberty
The persistent anemia of sickle cell disease slows childhood growth and delays puberty. As a result, adults with sickle cell disease are smaller on average than other adults
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Priapism
Males with sickle cell anemia are prone to episodes of priapism, prolonged and painful erections. Erections occur because blood accumulates in the penis. With sickle cell-associated priapism, the sickled RBCs obstruct outflow of blood from the penis, causing a painful, persistent erection. Repeated episodes of priapism can lead to impotence.
References
- "Hematology Clinical and Laboratory Practice"; Rodger L. Bick, M.D., Editor-in-Chief; 1993
- American Hematology Society: What is Sickle Cell Anemia?
- Medline Plus: Sickle Cell Anemia
- National Heart Lung and Blood Institute: What are the Signs and Symptoms of Sickle Cell Anemia?
- Sickle Cell Disease Association of America: What is Sickle Cell Disease?
