Sickle cell anemia

Alternative Names

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

Definition of Sickle cell anemia

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.)

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 exposed to low oxygen levels.


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

Signs and tests

Tests commonly performed to diagnose and monitor patients with sickle cell anemia include:


Patients with sickle cell disease need ongoing treatment, even when they are not having a painful crisis. They should take supplements of folic acid (essential for producing red blood cells) because red blood cells are turned over so quickly.

Expectations (prognosis)

In the past, sickle cell patients often died from organ failure between ages 20 and 40. Thanks to a better understanding and management of the disease, today, patients can live into their 50s or beyond.


Linda Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. – 1/31/2010

Red blood cells, sickle cell
Red blood cells, normal
Red blood cells, multiple sickle cells
Red blood cells, sickle cells
Red blood cells, sickle and pappenheimer
Formed elements of blood
Blood cells

ADAM Medical Encyclopedia

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