HematologyTest1HemoglobinopathiesandThalassemias

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victimsofadown
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HematologyTest1HemoglobinopathiesandThalassemias
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2014-03-19 05:45:26
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HematologyTest1HemoglobinopathiesandThalassemias
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HematologyTest1HemoglobinopathiesandThalassemias
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  1. How is type of Hgb quantified?
    • electrophoresis
    • Hgb is overall negative and will move toward positive value
    • cellulose acetate: pH 8.4
    • -apl----A2/C---S----F----A---H>+
    • *note-"A baby crawls, stands, goes faster, accelerates, then runs like hell
    • citrate agar: pH 6.0-6.5
    • +<C---apl---S---A/A2---F-->-
  2. How are Hgb disorders classified?
    • Qualitative
    • Abnormal AA sequencing in globin chain
    • Substitutions, deletion, addition, fusion
    • Hgb S,C,D,E
    • Quantitative
    • Decreased synthesis of normal Hgb chain
    • α and β thalassemia
  3. What is the cause of Hgb S? What does it appear as?
    • Valine replaces glutamic acid in AA 6 of the beta chain
    • sickled cells
  4. Clinical features of Sickle cell anemia (homozygous)
    • Affects .26% of African-Americans
    • Vascular occlusion (spleen, liver, kidney, bone marrow; slow blood flow in sinuses)
    • Generalized abnormal growth
    • Bone and joint abnormalities
    • Hepatomegaly
    • Enlarged heart
    • Spleen (autosplenectomy -a small, fibrotic, nonfunctional spleen- in adults)
    • Enlarged spleen in some children
    • Leg ulcers (can't heal due to poor circulation)
    • Retinal hemorrhage (improper blood flow)
    • CNS involvement, possible stroke 
    • Susceptible to microorganism infections
    • Jaundice
    • Hematuria
    • Sickle cell crisis
  5. What is a sickle cell crisis and what does it entail?
    • Aplastic (infections)
    • Hemolytic (acute splenic sequestration)
    • sudden weakness
    • rapid pulse
    • faintness
    • pallor oflips and mucous membranes
    • enlarged spleen
    • Vaso-occlusive
    • severe pain (crystallized cells try to go through small spaces)
    • may last 4-6 days to weeks
    • precipitated by infection, fever, acidosis, dehydration, exposure to extreme cold, stress, depression, anxiety
  6. Describe the laboratory findings in Sickle cell anemia (homozygous) - (std tests, blood smear, bone marrow, hgb electrophoresis)
    • Hemoglobin: 6-8 g/dL
    • hct: 18-24%
    • RBC: 2-2.5x106/μL
    • increased reticulocyte count: 5-20%
    • peripheral blood smear (sickle cells, target cells, HJ bodies, NRBC, polychromasia, fragmented cells)
    • Marrow: erythroid hyperplasia
    • Hgb electrophoresis: 80% S, 1-20% F
    • *note- no normal β chains
  7. Sickle cell anemia (homozygous) treatment and prognosis
    • Manage crisis (pain medication, antibiotic therapy, administer fluids)
    • Bone marrow transplantation (in the future maybe)
    • Gene therapy?
    • 85% of SS patients live to 20 years old
  8. Clinical features of Sickle cell trait (heterozygous)
    • Affects 8-10% of African-Americans
    • Usually asymptomatic
    • may have some sickling in kidney IN CRISIS
    • Crises occur in respiratory infections, air travel or deep-sea diving in unpressurized situations, anesthesia, congestive heart failt
    • *note- all of these involve lack of O2 that leads to tactoid formation
  9. Laboratory findings of Sickle cell trait (heterozygous) - (incl hgb electrophoresis)
    • Usually do not present with hemolytic anemia except in crisis
    • Peripheral blood smear does not normally have sickled cells except after crisis
    • Hemoglobin electrophoresis: 60% A, 40% S, elevated A2 
    • *note- all normal α w/ some normal β
  10. Treatment and prognosis of Sickle cell trait (heterozygous)
    • Prevent high-risk situations
    • Not necessary EXCEPT in crisis
    • Prognosis: genetic counseling is key
  11. What is the cause of Hgb C?  What does it appear as?
    • Lysine replaces glutamic acid in 6th position of beta chain
    • hgb C crystals in cells appear like bars of gold or off-center clumps in RBCs
  12. What are the clinical features of Hgb C disease?
    • Affects .02% of African-Americans
    • Mild chronic hemolytic anemia with splenomegaly
    • *note- occurs w/ age (not lack of O2)
  13. What are the laboratory findings of Hgb C disease? (peripheral blood smear, hgb electrophoresis)
    • normocytic, normochromic
    • slightly increased reticulocyte count
    • 50-90% target cells, few fragmented cells and microspherocytes, Hgb C crystals following splenectomy
    • *note- M0 no longer there to remove hgb C
    • Hgb electrophoresis: 95% C plus A2 and less than 7% F
  14. Hgb C disease tratment and prognosis
    • Treatment usually unnecessary
    • Prognosis is good
  15. clinical features of Hgb C trait, blood smear, electrophoresis
    • Affects about 2-3% African-Americans
    • Clinically asymptomatic
    • May show some targeting on peripheral blood smear
    • hgb electrophoresis: 60% A, 40% C
  16. What is Hgb SC disease? prognosis and symptoms, blood smear, hgb electrophoresis
    • RBCs have both Hgb S AND C
    • Is milder disease than Hgb SS
    • May cause more severe retinal damage and femoral head damage due to increased blood viscosity (no blood supply to head of femur)
    • blood smear: target cells, few intracellular Hgb C crystals, very few sickled cells
    • Hgb electrophoresis: 50% S, 50% C, <2% F
  17. What is the cause of Hgb D? What does it appear as?  Blood smear?
    • AA substitution of gultamine for glutamic acid on the 121st position of the beta chain
    • Both Hgb DD and DA are asymptomatic
    • Few target cells present on peripheral blood smear
  18. What is the etiology and cause of Hgb E disease?
    • More prevalent in US since migration of SE Asian refugees after Vietnam War
    • May be protective against malaria
    • cause: AA substitution of lysine for glutamic acid on the 26th position of the beta chain
  19. Describe the symptoms of Hgb E disease (+ smear, hgb electrophoresis)
    • Little or no anemia
    • Few target cells on smear
    • microcytic, hypochromic
    • hgb electrophoresis: 95-97% E plus A2 and 3-5% F
    • *note- no A
  20. Describe the symptoms of Hgb E trait (+ smear, hgb electrophoresis)
    • Asymptomatic
    • few target cells and microcytosis on smear
    • Hgb electrophoresis: 30% E plus A2 and 70% A
  21. Describe the geographical distribution of the thalassemias
    • α/β: found in SW Asia, Middle East, India
    • α: found Southern Africa
    • β: found in Southern Europe, Middle Asia
  22. What is the cause of Thalassemia, what does it result in, and what are the specific thalassemias?
    • Decreased rate of production of normal globin chains
    • Results in ppt of excess globin chains and increased destruction of RBCs
    • beta thalassemia has a deficiency in beta chains
    • alpha thalassemia has a deficiency in alpha chains
  23. What are the clinical features of beta thalassemia major
    • *note- homozygous state
    • enlarged spleen and liver
    • widening of skull and facial bones (from attempt to produce RBCs)
    • growth and mental retardation
    • fractures (thinning bones)
    • tumors in bone marrow
    • infections
    • iron overload (no use for it)
  24. What are the laboratory findings of beta thalassemia major (+smear, and hgb electrophoresis)
    • *note- homozygous state
    • Severe microcytic, hypochromic anemia
    • hgb less than 7g/dL
    • increased reticulocytes (up to 30%)
    • increased serum iron (no use for it)
    • smear: NRBC, A & P, thrombocytosis
    • hgb electrophoresis: NO A, increased F, normal to increased A2
  25. Describe the treatment and prognosis for Beta thalassemia major
    • treatment
    • regular blood transfusions
    • iron chelation therapy (too much Fe is bad)
    • splenectomy (prevents removal of cells)
    • bone marrow transplants
    • prognosis
    • variable
  26. Clinical features of beta thalassemia minor
    • *note- heterozygous state
    • Asymptomatic, because some beta chains are available
  27. Laboratory findings of beta thalassemia minor (incl hgb electrophoresis)
    • *note- heterozygous state
    • Mild form of chronic, microcytic, hypochromic anemia
    • Hgb levels from 10.5-13.9g/dL
    • Hgb electrophoresis: mostly A, slight increases to F and A2
  28. Beta thalassemia minor treatment and prognosis
    • Treatment: none usually needed
    • Prognosis: good
  29. What are the clinical features of alpha thalassemia major (all types) (incl Hgb electrophoresis)
    • Hydrops fetalis syndrome
    • No alpha chains produced
    • 4 defective alpha genese (2 per chr. 16)
    • Fetal RBCs contain Bart's hemoglobin, which has 4 gamma chains
    • Bart's hemoglobin has high affinity for O2 and will not give it up effectively
    • Most of the time the baby dies in utero or shortly after birth
    • Hemoglobin H disease
    • 3 defective alpha genes
    • Hgb with 4 beta chains
    • Decreased hgb and hct
    • smear: hypochromia, target cells, A&P
    • normal to slightly increased reticulocytes
    • Heinz bodies and Hgb H precipitant with supravital stains
    • *note- funny shapes appear (like S's) due to location of Hgb
    • Hgb electrophoresis: 5-40% H, some A, A2, Bart's
  30. What are the clinical features of Alpha thalassemia minor? Treatment?
    • *note- heterozygous
    • Asymptomatic
    • mild microcytic, hypochromic anemia
    • Hgb usually 9-11g/dL
    • Usually require no treatment
  31. All info about hereditary persistence of fetal hemoglobin (incl hgb electrophoresis)
    • Most prevalent in African-Americans
    • homozygous: 100% F
    • heterozygous: 15-30% F
    • *note- gamma chain production never declines
    • Fetal hemoglobin stain should ppt out any normal hgb, and will cause ghost cells of any that don't contain hgb F

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