Rbc disorders-3


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Rbc disorders-3

  2. 2. Clinical presentation• Anemia• Jaundice• Organomegaly• Delayed mile stones• Dysmorphic facies• Gall stones in young
  3. 3. Hemolytic anemias Common features:• Premature destruction of red cells• Elevated erythropoietin• Accumulation of hemoglobin degradation products
  4. 4. Destruction of RBCs• Physiologically takes place in mononuclear phagocytic system (Spleen,Liver, BM)• Terms: – Extravascular hemolysis – Intravascular hemolysis
  5. 5. Extravascular hemolysis• Caused by alterations that render the red cell less deformable• Clinical features: – Anemia – Splenomegaly & – Jaundice
  6. 6. Intravascular hemolysisCauses:• Mechanical injury – Prosthetic heart valves – Fibrin Thrombi in microcirculation or – Repetitive physical trauma • Marathon running• Complement fixation – Abs to RBCs• Intracellular parasites – Malaria• Exogenous toxic factors – Clostridial sepsis
  7. 7. Intravascular hemolysisManifested by:• Anemia• Hemoglobinemia• Hemoglobinuria• Hemosiderinuria, and• Jaundice• No splenomegaly
  8. 8. Intravascular hemolysis• Low serum haptoglobin• Methemoglobinemia• Renal hemosiderosis• Elevated serum bilirubin levels (UC)• Gall stones• Increased urobilinogen
  9. 9. Hemolytic Anemias - investigations• Peripheral smear – Fragmented RBC, nucleated RBC, polychromatophilic cells,• ↑ Reticulocytes• Bone marrow – ↑ Cellularity, M:E ratio 1:1 (Erythroid hyperplasia) – ↑ Normoblasts• Extramedullary hematopoiesis• ↑ Bilirubin – cholelithiasis• Hemosiderosis
  10. 10. Red cell sequestration in splenic sinusoids
  11. 11. There are numerous fragmented RBCs seen here. Some of the irregular shapes appearas "helmet" cells. Such fragmented RBCs are known as "schistocytes" and they areindicative of a microangiopathic hemolytic anemia (MAHA) or other cause forintravascular hemolysis. This finding is typical for disseminated intravascularcoagulopathy (DIC).
  12. 12. Polychromatophilic cells
  13. 13. Reticulocyte
  14. 14. Normal marrow fragments and cell trails. Fig. 1.24
  15. 15. Hereditary Spherocytosis (HS)
  16. 16. • Inheritance – AD (75%) – Compound heterozygosity• Northern Europe (1 in 5000)• Defective cell membrane skeleton• Spherical & less deformable RBC• Splenic sequestration % destruction
  17. 17. Pathogenesis• Cytoskeletal defect• The life span of the affected red cells 10 to 20 days
  18. 18. Hereditary Spherocytosis• Spectrin – Major protein of membrane cytoskeleton• Two polypeptide chains – α and β• Spectrin is tethered to the inner surface of cell membrane by ankyrin, protein 4.2 to trans membrane transporter band 3
  19. 19. Hereditary Spherocytosis• Gene mutation involving ankyrin, protein 4.2, spectrin or band 3 reduce membrane stability• Spontaneous loss of cell membrane• ↓ Cell surface to volume ratio – spheroidal shape• Spherocytes are less deformable and vulnerable to splenic sequestration and destruction
  20. 20. Schematic representation of the red cell membrane cytoskeleton and alterations leading to spherocytosis and hemolysis
  21. 21. Red cell sequestration in splenic sinusoids
  22. 22. Hereditary Spherocytosis• Clinical features – Anemia - varies – Splenomegaly – Jaundice• Aplastic crisis – triggered by parvovirus infection of marrow precursor• Hemolytic crisis
  23. 23. Hereditary Spherocytosis• Hb – normal / decreased• MCV – decreased• MCHC – increased more than 36 gm/dl• PBS – Spherocytes – Reticulocytosis – more than 8% – Nucleated RBC• Osmotic fragility test
  24. 24. Osmotic fragility test
  25. 25. Osmotic fragility test
  26. 26. Hereditary Spherocytosis
  27. 27. Hereditory Spherocytosis
  28. 28. The size of many of these RBCs is quite small, with lack of the central zone of pallor.These RBCs are spherocytes. In hereditary spherocytosis, there is a lack of spectrin, akey RBC cytoskeletal membrane protein. This produces membrane instability thatforces the cell to the smallest volume--a sphere. In the laboratory, this is shown byincreased osmotic fragility. The spherocytes do not survive as long as normal RBCs.
  29. 29. Reticulin stain
  30. 30. Hereditary Spherocytosis• Osmotic fragility test – Confirmatory test• Spherocytes are vulnerable to osmotic lysis induced in vitro by hypotonic salt solution• Hemolysis starts at 0.8 gm% and completes between 0.5 – 0.4 gm%
  31. 31. G6PD - deficiency
  32. 32. Name the two important products of HMP shunt • NADPH • Ribose-5-Phophate
  33. 33. G6PD - deficiency• Erythrocytes are vulnerable to oxidant induced injury• Intracellular reduced glutathione (GSH) inactivates oxidant• G6PD is needed for maintaining adequate quantity of GSH
  34. 34. G6PD - deficiency• Sulfhydral group of globin chain of Hb is oxidized.• Hb precipitate to form Heinz bodies – damage the cell membrane• Bite cells• Intravascular hemolysis
  35. 35. Heinz bodies
  36. 36. G6PD - deficiencyOxidant stress• Drugs – Antimalaria – primaquine – Sulfonamide – Sulfones – Nitrofurans – Analgesic• Infection – Viral hepatitis, pneumonia, typhoid fever• Food – fava beans (Favism)
  37. 37. G6PD - deficiency• X – linked disorder• More than 350 G6PD genetic variants are recognised• G6PD A- – 10% of American black – Normal enzyme activity in reticulocyte – Unstable enzyme – half time 13 days (62 days)• G6PD Mediterranean – Severe ↓ enzyme activity – less than 10% – Severe hemolysis
  38. 38. G6PD - deficiency• Asymptomatic• Infectious disease / drug exposure• Sudden onset of anemia• Hemoglobinuria, Hemoglobinemia• Abdominal / low back pain• Self limited
  39. 39. G6PD - deficiency• PBS – Spherocytes, erythrocyte fragments, bite cells, Heinz bodies, polychromasia• Measurement of enzyme activity – Fluorescent spot test – Dye reduction test
  40. 40. Polychromatophilic cells
  41. 41. PNHParoxysmal Nocturnal Hemoglobinuria
  42. 42. • Incidence of 2 to 5 per million
  43. 43. Acquired Membrane disorder• Paroxysmal nocturnal hemoglobinuria (PNH) is a disease that results from acquired mutations in the phosphatidylinositol glycan complementation group A gene (PIGA), an enzyme that is essential for the synthesis of certain cell surface proteins
  44. 44. Attachment of proteins to cell membrane• Transmembrane proteins• GPI linked proteins: The others are attached to the cell membrane through a covalent linkage to a specialized phospholipid called glycosylphosphatidylinositol (GPI).• In PNH, these GPI-linked proteins are deficient because of somatic mutations that inactivate PIGA
  45. 45. • PNH blood cells are deficient in three GPI-linked proteins that regulate complement activity: 1. decay–accelerating factor, or CD55 2. Membrane inhibitor of reactive lysis, or CD59 3. C8 binding protein.• Of these factors, the most important is CD59, a potent inhibitor of C3 convertase that prevents the spontaneous activation of the alternative complement pathway.
  46. 46. • Red cells, platelets, and granulocytes deficient in these GPI-linked factors are abnormally susceptible to lysis or injury by complement• In red cells this manifests as intravascular hemolysis• The hemolysis is paroxysmal and nocturnal
  47. 47. Urine samples from a typical PNH patient
  48. 48. PNH is diagnosed by flow cytometry
  49. 49. Major vein thrombosis• Thrombosis is the leading cause of disease- related death in individuals with PNH• Other causes: – Protein C / S deficiency – Factor V Leiden – Hyperfibrinogenemia
  50. 50. END
  51. 51. Dr.CSBR.Prasad, M.D.,Associate Professor of Pathology,Sri Devaraj Urs Medical College, Kolar-563101, Karnataka, INDIA. csbrprasad@reiffmail.com