HematologyTest1IntracorpuscularDefects

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victimsofadown
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267065
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HematologyTest1IntracorpuscularDefects
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2014-03-19 04:09:42
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HematologyTest1IntracorpuscularDefects
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HematologyTest1IntracorpuscularDefects
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  1. Describe the RBC life span and survival (normal and w/ anemia)
    • normal: 120 days then recycled/reused
    • anemic: lifespan and survival rate shortens
  2. Describe the clinical features of hemolysis
    • Decreased RBC count
    • Accelerated Hgb breakdown
    • Increased bilirubin (jaundice in severe cases)
    • Decreased haptoglobin
    • Hemosiderin in kidney tubules
    • Increased urobilinogen in urine and feces
    • Hemoglobin in urine
  3. Describe the bone marrow response to hemolysis.  Peripheral blood.
    • Marrow
    • Erythroid hyperplasia 
    • skeletal deformities (failure to thrive state)
    • Blood
    • NRBC
    • increased reticulocytes
    • Howell-Jolly bodies
  4. Describe the etiology of hereditary spherocytosis
    • Spectrin and ankyrin deficiency (causes lack of membrane which gives sags/imperfections)
    • overconditioning of RBCs by spleen (preens until RBC membrane is taught and becomes sphere)
  5. Describe the clinical features of hereditary spherocytosis
    • Age of presentation varies
    • Jaundice in the young/elderly
    • anemia (mild to severe)
    • enlarge spleen (tries to be garbage disposal)
  6. Describe the lab findings for hereditary spherocytosis (special tests, indices, blood smere)
    • hyperbilirubinemia
    • haptoglobin variability reduced
    • no classic signs of intravascular hemolysis
    • increased reticulocytes
    • average hgb is 12-13g/dL
    • MCV and MCH vary
    • MCHC is usually increased above 36%
    • Peripheral blood: spherocytes, may have A & P
  7. What laboratory tests will contribute to diagnosis of hereditary spherocytosis
    • Osmotic fragility - will lyse at lower NaCl concentrations
    • Autohemolysis test - 10-50% fragile in HS vs .2-2% in normal RBCs
    • (sterile incubation of RBCs in own plasma for 48 hours, ATP and glucose needed to keep "leaky" sodium out of cell (pump), cells are fragile in glucose depletion)
    • RBC membrane protein studies
  8. Describe the treatment of hereditary spherocytosis
    • Splenectomy in many cases
    • deferred until after 6 years in children due to infections with streptococcus pneumoniae (remember, cells still work even if they look funny)
  9. Describe the etiology of hereditary elliptocytosis
    • Spectrin and/or protein deficiency or dysfunction
    • Membrane is weakened in stress (↑ blood pressure, dehyration, overhydration)
  10. What are the clinical features of hereditary elliptocytosis
    • most cases are asymptomatic
    • few have traditional symptoms of severe hemolytic anemia (HA)
    • Almost every RBC is eliptocytic
  11. Describe the laboratory findings in hereditary elliptocytosis
    • Most cases of HE have a mild, compensated HA with minimal hemolysis
    • slight reticulocytosis
    • decreased haptoglobin levels
    • normal RBC indices
    • many cases show no evidence of a hemolytic process
    • *note- in most cases people are fine
  12. What laboratory tests can help diagnose hereditary elliptocytosis
    • Osmotic fragility and autohemolysis tests are usually normal in mild cases
    • RBC membrane studies
  13. Describe the treatment for hereditary elliptocytosis
    • No treatment necessary (most)
    • More severe cases may require splenectomy
  14. Describe the etiology of hereditary stomatocytosis and hereditary xerocytosis
    • Permeable membrane permits cation "leaks" into and out of RBC
    • Hereditary stomatocytosis: Na leaks into cell and K leaks out of cell
    • water enters the cell with Na and RBCs swell
    • Heredtary xerocytosis: water exits the cell with sodium and RBCs become dehydrated
  15. Describe the clinical features of hereditary stomatocytosis and hereditary xerocytosis
    most cases have no severe hemolytic symptoms
  16. Describe the laboratory findings of hereditary stomatocytosis
    • Increased MCV
    • decreased MCHC
    • macrocytosis
    • stomatocytes (bowl like)
  17. Describe the laboratory findings of hereditary xerocytosis
    • target cells (extra membrane)
    • small echinocytes (reversible)
    • increased MCHC
  18. Describe the treatment options for hereditary stomatocytosis and hereditary xerocytosis
    • hereditary stomatocytosis: patients respond well to splenectomy
    • hereditary xerocytosis: patients do not benefit from splenectomy
  19. G-6-P deficiency etiology
    • Enzyme failure to catalyze reactions to reduce glutathione in RBC
    • glutathione is necessary to protect hgb from oxidative denaturation
    • oxidation results in ppt of irreversibly denatured hgb (Heinz bodies) 
    • *note- this will reduce O2 tfer capacity
    • x-linked recessive, but symptoms show in patients w/ infections, chemicals, fava beans (some cases)
  20. Describe the clinical features of G-6-PD
    • Many are asymptomatic
    • Most symptoms are induced (often by drugs), and include...
    • back pain
    • hemoglobinuria
    • jaundice
    • others present with more severe hemolytic symptoms
  21. Describe the laboratory findings of G-6-PD
    • 2-3 days after drug use, or other symptom inducer
    • decreased RBC
    • decreased Hgb
    • normocytic, normochromic anemia
    • Severe hemolytic reactions
    • decreased hgb and hct
    • hemoglobinuria (brown to black)
    • elevated bilirubin
    • markedly decreased on absent haptoglobin levels
    • no major changes in WBC or platelets
  22. What lab tests are associated with G-6-PD?
    • Heinz body staining (screen)
    • G-6-PD assay to determine true deficiency
  23. What does G-6-PD look like in a wright stain?
    vacuole-looking structures at the edge of an RBC
  24. Describe the etiology of pyruvate kinase deficiency
    • Deficiency causes decreased ATP production in Embden-Meyerhof pathway
    • leads to cell water loss and shrinkage, distortion of cell shape, increased membrane rigidity
    • Abnormal cell types are destroyed by spleen and liver
  25. What are the clinical features of Pyruvate kinase deficiency?
    • Severe cases are jaundiced at birth
    • Less severe diagnosed at childhood or young adult
  26. Describe the lab findings of pyruvate kinase deficiency
    • Less severe cases
    • normocytic, normochromic anemia (no associated cell type)
    • varying reticulocytosis
    • More severe cases
    • decreased hgb and hct
    • polychromasia
    • NRBC
    • anisocytosis and poikilocytosis
    • increased bilirubin
    • decreased haptoglobin
  27. What are the special lab tests associated with pyruvate kinase deficiency
    Pyruvate kinase enzyme assay (standard for newborns)
  28. Describe the treatment of pyrufvate kinase deficiency
    • Possible transfusion
    • Some may benefit from splenectomy
  29. Describe the etiology of methemoglobin reductase deficiency
    • deficiency causes increased levels of methemoglobin
    • methemoglobin IS NOT an effective hemoglobin carrier
    • may not be a problem unless exposed to drugs (eg. meth)
  30. clinical features of methemoglobin reductase deficiency
    cyanosis (turn blue)
  31. laboratory findings of methemoglobin reductase deficiency
    mild compensatory polycythemia (erythroid hyperplasia)
  32. Treatment of methemoglobin reductase deficiency
    removal of offending drug

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