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Current Peds-Chapter 30: Sickle Cell Disease

Terms in this set (17)

--S/S are related to the hemolytic anemia, tissue ischemia, and organ dysfunction caused by vaso-occlusion.

--Most severe in children with sickle cell anemia or sickle beta-thalassemia.

--Physical findings are normal at birth, and symptoms are unusual before 3-4 months of age because high levels of fetal hemoglobin inhibit sickling.

--A moderately severe hemolytic anemia may be present by age 1. This causes pallor, fatigue, and jaundice, and predisposes to the development of gallstones during childhood and adolescence.

--Intense congestion of the spleen with sickled cells may cause splenomegaly in early childhood and results in functional asplenia as early as 3 months of age in sickle cell anemia. This increases risk for overwhelming infection with encapsulated bacteria, particularly pneumococci.

--Up to 30% of pt's experience 1 or more episodes of acute splenic sequestration, characterized by sudden enlargement of the spleen with pooling of red cells, acute exacerbation of anemia, and, in severe cases, shock and death.

--Acute exacerbation of anemia also occurs with aplastic crises, usually caused by infection with human parvovirus & other viruses.

--Recurrent episodes of vaso-occulsion and tissue ischemia cause acute and chronic problems.

--Dactylitis, or hand-and-foot syndrome, is the most common initial symptom of the disease and occurs in up to 50% of children with sickle cell anemia before age 3.

--Recurrent episodes of abdominal and musculoskeletal pain may occur throughout life.

--Overt strokes occur in about 11% of children with SCD and tend to be recurrent. Recurrence is significantly reduced with chronic red cell transfusions.

--Acute chest syndrome: characterized by fever, pleuritic chest pain, and acute pulmonary infiltrates with hypoxemia, is caused by pulmonary infection, infarction, or fat embolism from ischemic bone marrow.

--All tissues are susceptible to damage from vaso-occulsion, and multiple organ dysfunction is common by adulthood in those with sickle cell anemia or sickle beta-thalassemia.
--Children with sickle cell anemia generally show a baseline Hgb of 7-10 g/dL. This may fall to life-threatening levels at the time of a splenic sequestration or aplastic crisis.

--Baseline reticulocyte count is markedly elevated.

--The anemia is usually normocytic or macrocytic, and the peripheral blood smear typically shows the characteristic sickle cells as well as numerous target cells.

--Pt's with beta-thalassemia also generally have a low MCV and hypochromia. Also tend to have less hemolysis and anemia.

--Pt's with sickle hemoglobin C disease have a fewer sickle forms and more target cells, and the Hgb level may be normal or only slightly decreased because the rate of hemolysis is much less than sickle cell anemia.

--Most infants with sickle hemoglobinopathies born in the US are identified by neonatal testing. Results indicative of possible SCD require prompt confirmation with hemoglobin electrophoresis.

--Children with sickle cell anemia and sickle beta-thalassemia have only Hgb's S, F, and A2. Persons with beta-thalassemia have a preponderance of Hgb S with a lesser amount of hemoglobin A and elevated A2.

--Pt's with sickle hemoglobin C disease have equal amounts of hgb's S and C.

--The use of solubility tests to screen for the presence of sickle hgb should be avoided because a negative result is frequently encountered in infants with sickle cell disease, and a positive result in an older kid does not differentiate sickle cell trait from sickle cell disease. Do not identify hemoglobin variants other than S.

--Hemoglobin electrophoresis is always necessary to accurately identify a sickle disorder.