Sickle cell anemia one of the hemolytic anemias

Sickle cella nemia

1. Sickle Cell Anemia

2. Definitions: It is an autosomal recessive disease characterized by abnormal hemoglobin called Hbs .

3. Pathogensis : It is resulted due to substitulated of amino acid No.6 in beta chain by valine instead of glutamic acid which affects the normal physical properties of hemoglobin distortion of RBCs shape when exposed to low oxygen tension rigid cells with sickle shape obstruct the blood vessels and destroyed. Infarction may occur in many organs as spleen, kidney, brain, heart .

4. The disease is manifested when the patient is homozygous for sickle call gene. In this care 90% of Hb is Hbs and the rest is HbF and Hb A2 with No HbA . When the patient I heterozygous for gene, it is said to be have sickle cell trait which has a benign clinical course. RBCs contain mixture of HbS which varies from 35 –45% and HBA. In that cases sickling doesn’t occur under normal physiologic condition. Symptoms may occur in sever hypoxemia as in shock or flying at high altitudes. It is believed that sickle cell confere a degree of resistance to faliciparum malaria as HbS resist invasion by malaria

5. Clinical picture : Sickle cell anemia is prevalent in Negro. Manifestations appears later on at the 2nd of first year due to presence of large amount of HBF in young infants. Manifestation of anemia are those of chronic hemolytic anemia crises.  

6. Vaso -occlusive crisis : It is precipitated by hypoxemia, pneumania , general anathesia , bleeding or shock. It may present by : - Hand –foot syndrome or sickle cell dactylitis ; - cause by infarction in the small bones of the extremities. Strokes: due to cerebral artery occlusion hemiplegia pulmonary infarction acute chest syndrome. Splenic infarction autosplenectomy . Kidney Hematuria .

7. Aplastic Crisis : Sudden bone marrow hypoplasia manifested by fall of HB, reticulocytes , WBCs and platelets . It usually results from parvovirus infection and lasts for 10 –14 days and recover spontaneously

8. Hemolytic Crises : The patient presented as a case of acute hemolytic anemia . It is usually caused by infections Hyper hemolytic crises : _It is due to coincident G-6-OD deficiency

9. Sequestration crises : Pooling of blood in the spleen massive enlargement of the spleen and signs of circulatory collapse . Treatment by good hydration and blood transfusion. Megaloblastic Crises : Due to increased need for folic acid which is required for erythropoiesis .

10. Spleen is initiatly enlarged and finally it become small and fibrotic due to repeated infarction functional hyposplenism with reduced phagocytosis increased susceptibility to infection with pneumococci and hemophilus influenza . Sickle anemia related cardiomyopathy : due to vaso occulusive crises, hemosiderosis .

11. Laboratory manifestation : General laboratory manifestation of chronic hemolytic anemia. Specific finding in Hb -SS disease : _ Sickle cells in peripheral blood film the sickling test. HB electrophersis : _ shows presence of HB-S.

12. Treatment : Folic acid therapy. Vaccination against pneumoccoci , H influenza and hepatitis B Prophylactic : _ long acting penicillin are given every 4 weeks. Repeated packed RBCs transfusion to correct anemia and prevent crises. Iron chelating agents may be needed to prevent hemosiderosis .

13. Auto Immune Hemolytic Anemia Diffenition : It is a type of hemolytic anemias resulting from abnormal antibodies directed against red cell antigens causing hemolysis .

14. Etiology : Idiopathic Secondary to: Malignancy Collagen diseases Chronic inflammatory disease Chronic as Epstein Barr virus, hepatitis B, Mycoplasma Drugs.

15. Clinical picture: It may be acute transient type pallor) Jaundice, fever, hemoglobinurea ). Chronic type has prolonged course and usually secondary to an under lying systemic disease.

16. Laboratory manifestation: Normochromic normocytic anemia. Coombs test : the hallmark of autoimmune hemolytic anemia is a positive direct coomb’s test. Hyperplastic bone marrow.

17. Treatment : Packed RBCs transfusion. Treat the 1ry cause if present. In idiopathic type: Corticosteroid, cytotoxic drugs. Splenectomy done if no response to medication.