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31 Cards in this Set
- Front
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Hemoglobinemia
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Increased Hb levels in blood plasma
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Hemoglobininuria
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Increased Hb levels in urine
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Why is there a decrease in serum haptoglobin levels in intravascular hemolytic anemia?
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In intravascular hemolysis free hemoglobin will be released into circulation and hence haptoglobin will bind the Hb. This causes a decline in Hp levels.
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Extravascular Hemolytic Anemia
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Splenic marcophages phagocytose RBCs and thus haptoglobin levels are normal
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Where is Heme degraded in intravascular hemolytic anemia?
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Hepatocytes; degraded into Fe and porphyrin
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Where is Heme degraded in extravascular hemolyic anemia?
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Splenic macrophages; degraded into heme and porphyrin
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Hereditary Spherocytosis
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AD; RBC cytoskeletal membrane protein defects render erythrocytes spheroidal, less deformable, and vulnurable to splenic sequestration and destruction
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Hereditary Spherocytosis Pathophysiology
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Defects in membrane skeletal proteins lead to defective SPECTRIN; this causes RBC to become unstable and they assume a spheroidal shape (spherocytosis)
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Glucose-6-Phosphate Dehydrogenase Deficiency
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Normally reduces glutatihone (which protects RBC from oxidative injury); if G6PD is deficient, oxidant stresses induce hemoglobin denaturation (Heinz bodies)
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Heinz Bodies
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Precipiated denatured hemoglobin, which occurs due to oxidant stress and lack of reduced glutathione in G6PD deficiency
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Are ROS generated by ferrous or ferric iron?
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Ferric
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Pyruvate Kinase Deficiency
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AR; defect in pyruvate kinase -> decreased ATP production -> rigid RBC -> hemolysis
2,3 BPG accumulation (which is trying to offset the effects of the anemia) The final step of energy generating stage of glycolysis is blocked |
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What is the mutatoin producing sickle cell anemia?
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HbS mutation is a single amin oacid replacement in Beta chain (substitition of normal glutamic acid with VALINE)
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What is the pathogenesis of sickle cell anemia?
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Deoxygenated HbS polymerizes; low 02 or dehydration precipitates sickling (since there's more contact)
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What is the evolutionary function of sickle cell anemia?
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Protective against malaria in heterozygotes
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Why are newborns initially asymptomatic with sickle cell anemia?
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Increased levels of HbF (until about 6 months, when HbS ramps up in long bones)
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What are some complications of sickle cell anemia?
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Aplastic crisis (due to B19 infection)
Autosplenectomy (repeated episodes of vaso-occlusion have caused progressive scarring and shrinkage of spleen) |
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What kind of variables affect sickling of cells?
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Severity of disease is enhanced by any variable that reduces the affinity of HbS for oxygen (low oxygen, decreased pH, increased pC02, dehydration, increased 2,3 BPG)
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Why can you use electrophoresis to diagnose hemoglobinopathies?
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Because point mutations in globin chains alter the properties of hemoglobins
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How would HbS compare to HbA on an electrophoretic gel?
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HbA would be farther along the gel towards the anode then HbS
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A-Thalassemia Mutatoin
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Defect; alpha globin gene mutation -> decreased alpha-globin synthesis
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Newborns with Alpha-Thalassemia
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Excess unpaired gamma-globin forms gamma4 tetramers (Hb Barts); each tetramer can't deliver oxygen to tissues; leads to hydrops fetalis
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Hydros Fetalis
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4 bad alpha-globin genes results in accumulation of fluid in fetal compartments
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B-Thalassemia Mutation
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Point mutations in splicing sites and promoter regions for B-globin
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B-thalassemia Minor
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Heterozygote; B chain is UNDERPRODUCED; usually asymptomatic
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B-Thalaseemia Major
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Homozyote; B chain is absent -> severe anemia requiring blood transfusion (secondary hemochromatosis)
Marrow expansion ("crew cut" on skull xray) -> skeletal deformities. Chipmunk facies |
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How can you differentiate between folate and B12 megaloblastic anemias?
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In folate deficiency, the gastric atrophy and neurologic changes associated with VB12 deficiency do not occur.
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Macrocytic Anemia
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Impaired DNA synthesis -> maturation of nucleus delayed relative to maturation of cytoplasm
(since RNA synthesis is not and cytoplasmic protein development proceeds at normal pace) |
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Iron Deficiency Anemia
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Deficient heme synthesis due to inadequate iron supply; protophoryin IX accumulates
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Sideroblastic Anemia
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Sufficient iron supply but insufficient heme synthesis
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Basis for microcytic hypochromatic RBC morphology in iron deficiency anemia and sideroblastic anemia
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Heme is required to inactivate heme kinase; in the absence of heme, active heme kinase phosphorylates and inactivates EIF2 thereby blocking protein synthesis -> erythroid precursor cells remain small in size (microcytic); the absence of heme results in a hypochromic morphology
Thus iron deficiency or sideroblastic anemias are microcytic, hypochromic anemias |