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Hemoglobinopathy -sickle cell anemia

Sickle cell anemia-definition, pathophysiology, hematologic, diagnostic findings and treatment

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Hemoglobinopathy -sickle cell anemia

  2. 2. Case 1 • A 20 year old boy complaints of episodic pain in both upper and lower limb for past 2 months. • Pain is associated with tenderness in both arms and calf muscles. • He also has fever and tachycardia during the episode. • 2 days back he had severe chest pain and fever along with decrease oxygen saturation. What is the diagnosis?
  3. 3. Objectives • Definition • Genetics • Pathophysiology • Clinical features • Haematologic finding • Diagnostic test • Treatment
  4. 4. SICKLE CELL ANEMIA • Hereditary hemoglobinopathy • Caused by point mutation at the sixth position of the beta β-globin chain leading to the substitution of a valine residue for a glutamic acid residue. • Characterised by red blood cell that assumes an abnormal rigid and sickle shape.
  5. 5. Geographical distribution • HbS is prevalent in Africa ,Mediterranean countries and India. • Individuals with sickle cell trait are resistant to the lethal effects of falciparum malaria
  6. 6. GENETICS
  7. 7. Pathogenesis • When HbS is deoxygenated,molecules of Hb polymerize to form ‘tactoid’. • These distorts the red cell membrane and produce the sickle shaped cell. • Reversible-re-oxygenation. • Irreversible-distorted red cell membrane became permanent. • Hb F inhibits the polymerization.
  9. 9. If one parent has sickle cell trait(HbAS) and the other does not carry the hemoglobin at all(HbAA),then none of the children will have sickle cell in two(50%) will get sickle cell trait
  10. 10. If both the parent have sickle cell trait (HbAS)there is a one in four (25%)children will have sickle cell in four will be in two(50%) will be sickle cell trait.
  11. 11. If one parent has (HbAS) and the other has sickle cell anemia(HbSS)th ere is a one in two (50%)will get sickle cell trait and one in two (50%)will get sickle cell anemia
  12. 12. If one parent has sickle cell anemia(HbSS) and the other is completely (HbAA)unaffected then all the children will have sickle cell trait none will have sickle cell anemia
  13. 13. CLINICAL FEATURES • Vaso-occlusivecrisis: bone pain,tachycardia,sweating • Sickle chest syndrome:bone marrow infarction - fat emboli in lungs-causes sickling-ventilatory failure. • Sequestration crisis:Massive splenic enlargement and priapism • Aplastic crisis:Infection with human parovirus B19-low Hb-causes heart failure-reticulocyte count-low
  15. 15. HAEMATOLOGICAL FINDINGS PERIPHERAL SMEAR FINDINGS: • Anisopoikilocytosis. • Red cells are normocytic normochromic. • Sickle cell,Target cell,ovalocyte and howell jolly bodies are seen. • Howell jolly body-prominent feature of hypofunction of spleen.
  16. 16. Howell jolly bodies  These inclusions are nuclear remnant seen in redcells,intermediate/ late normoblast.  Observed in megaloblastic anemias and post splenectomy as the pitting function of the spleen is lost.
  17. 17. Bone marrow of sickle cell anemia
  18. 18. DIAGNOSIS • SICKLING TEST: 2%Sodium metabisulphite or sodium dithionate to blood. • Hb ELECTROPHORESIS • HbF ESTIMATION • HPLC • HbS SOLUBILITY • FAMILY STUDIES
  20. 20. TREATMENT • Folic acid:supplement diet • Educating the patient -awareness • Hydroxyurea:Reduce the incidence of sickling crisis-elevate the level of HbF-carry more O2 • Blood transfusion:Indicated in severe anemia,surgery,pregnancy.