About sickle cell disease

September 1, 2012
Angela M Ellison, Md Msc

To prevent the morbidity and mortality associated with emergency complications of sickle cell disease, it's important that providers recognize the signs and interpret what lab and imaging results mean.

Key Points

Sickle cell disease (SCD) refers to a group of inherited hemoglobinopathies characterized by the presence of sickle hemoglobin (HbS) in red blood cells (RBCs).1 The primary defect in SCD lies at the level of the β-globin chain of Hb in which glutamic acid is substituted for valine at the sixth position, resulting in the production of HbS. Under deoxygenated conditions, HbS polymerizes, causing RBCs to assume the classic sickle shape.

As sickle RBCs travel through blood vessels, they adhere to each other and the vessel's wall, resulting in occlusion of the blood vessels. Complications associated with SCD develop as a result of recurrent infarction and ischemia of tissues and organs. Fetal Hb (HbF) prevents the polymerization of HbS; therefore, the initial presentation of vaso-occlusive complications corresponds with the normal decline in HbF, with symptoms appearing as early as 6 months.

Sickle cell disease is manifested clinically as chronic hemolytic anemia, unpredictable acute complications, and variable degrees of chronic organ damage.1 The 4 genotypes that account for most SCD in the United States are sickle cell anemia (HbSS), sickle hemoglobin C disease (HbSC), and the sickle thalassemias (Sβ+- and Sβ°-thalassemia). The distinction between genotypes is often based on the severity of clinical manifestations.

Early recognition and aggressive management of acute illness can prevent much of the morbidity and mortality associated with SCD.1 Therefore, it is imperative that primary care providers and emergency medicine providers remain up-to-date on the treatment of complications of this disease.