Snapshot A radiograph of a 25-year-old patient of Nigerian descent shows bilateral hip deformities with increaseing density of the bone. Her hemoglobin electrophoresis reveals predominantly Hgb S, slighly increased Hgb F, and no Hgb A. Introduction An autosomal recessive disorder due to abnormal hemoglobin Hgb S tetramers polymerize causing sickling of deoxygenated RBCs Homozygotes have systemic / hematologic disease Heterozygotes are usually asymptomatic and have some resistance to malaria may have painless hematuria as a result of renal papillary necrosis Blacks are most commonly affected Acute vaso-occlusive epsisodes are often precipitated by infection hypoxia dehydration Presentation Symptoms mainly a result of vaso-occlusive crises chest pain bone pain fever strokes priapisms abdominal pain autosplenectomy gallstones in children from intravascular hemolysis dactylitis (painful swelling of the hands and feet) up to 50% of children under three will develop Physical exam splenomegaly jaundice pallor bone/joint tenderness Evaluation Labs normocytic or microcytic anemia high reticulocyte count Histology peripheral blood smear shows sickling (see above) bone marrow smear is hypercellular blood smear will show Howell-Jolly bodies Imaging check chest radiograph for chest syndrome lumbar radiograph may show "fish mouth vertebrae" Diagnosis by peripheral blood smear or hemoglobin electrophoresis Differential Thalassemia, osteomyelitis, pneumonia, rhuematic fever, and acute abdomen Treatment Treat acute attacks with hydration oxygen analgesia For severe attacks and chest syndrome perform an exchange transfusion Chronic hydroxyurea decreases frequency and severity of crises Pneumococcal vaccine to prevent pneumococcal sepsis be alert for infection by encapsulated organisms due to functional asplenia Prognosis, Prevention, and Complications Functional asplenia by an early age at risk for encapsulated bacterial infection most common infectious agent is S. pneumoniae e.g. salmonella osteomyelitis may result in splenic sequestration of RBCs Aplastic anemia/crisis with parvovirus B19 infection will have low reticulocyte count may also have aplastic anemia as a result of folic acid deficiency supplement with daily folate Prophylaxis for children daily folate penicillin until 5 years of age hydroxyurea pneumococcal vaccination Avascular necrosis of the femoral head MR is the most sensitive test MI Stroke treatment is exchange transfusion Gallbladder diseae Renal disease can present as the inability to concentrate urine (hyposthenuria), resulting in frequent urination (polyuria) Infection Retinopathy Chronic hemolysis