Sickle Cell Anemia

Sickle cell anemia is an inherited blood disorder that affects the hemoglobin molecule in red blood cells. Hemoglobin is the part of the red blood cells that carries oxygen from the lungs and delivers it to the rest of the body.

How Cells Become "Sickled" or an Irregular Shape

In sickle cell anemia, the hemoglobin molecule is abnormal such that under conditions of low oxygen levels, neighboring hemoglobin molecules tend to stick together in long rods in a process called polymerization.

Polymerization distorts the shape of the red blood cell changing it from the usual biconcave disk shape to an irregular sickled shape. These sickled red blood cells have a tendency to stick to the walls of blood vessels causing the clogging of blood vessels known as vaso-occlusion, which compromises the blood supply to organs and tissues. This leads to the classic pain crisis for which sickle cell anemia is most recognized as well as chronic organ damage and other complications.

How Sickle Shaped Cells Cause Anemia

Red blood cells live about 120 days in the bloodstream, but sickled red cells die after about 10 to 20 days. Because they cannot be replaced fast enough, the blood is chronically short of red blood cells, leading to a condition called anemia. Anemia can lead to shortness of breath, fatigue, exercise intolerance, and delayed growth and development in children. The rapid breakdown of red blood cells is called hemolysis and may also cause yellowing of the eyes and skin, or jaundice.

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