MLAB 1415: Hematology Keri Brophy-Martinez
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Transcript of MLAB 1415: Hematology Keri Brophy-Martinez
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MLAB 1415: HEMATOLOGYKERI BROPHY-MARTINEZHemolytic Anemia: Membrane Defects
Part One
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INTRODUCTION
Defects due to abnormalities in membrane proteins or lipids
Defects alter membrane’s stability, shape, deformability and permeability
Hemolysis occurs extravascularly
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OVERVIEW:MEMBRANE DEFECTS Skeletal protein abnormalities
◦ Vertical Separating of lipid bilayer from skeletal lattice Result in decrease in surface area-to-volume
ratio..spherocyte◦ Horizontal
Disruption of skeletal lattice Membrane destabilizes Cell fragmentation..poik
Lipid composition abnormalities◦ Excess cholesterol accumulates in the outer
bilayer of the RBC◦ Acanthocyte
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CONDITIONS ASSOCIATED WITH MEMBRANE DEFECTS
◦ Hereditary spherocytosis◦ Hereditary elliptocytocytosis◦ Hereditary pyropoikilocytosis◦ Overhydrated and dehydrated hereditary
stomatocytosis◦ Membrane lipid disorders◦ Paroxysymal noctural hemoglobinuria
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DISORDERS Hereditary spherocytosis (HS)
◦ Defect in ankyrin & spectrin◦ Results in the formation of fragile spherocytic red cells.◦ Spherocyte becomes less flexible and more permeable to
Na+
◦ Tends to affect Northern Europeans ◦ Inherited
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HEREDITARY SPHEROCYTOSISCLINICAL FINDINGS
Varies in severity Compensated hemolytic disease Anemia- varies with severity Intermittent jaundice Splenomegaly Cholelithiasis: pigment bile stones from
increased bilirubin breakdown
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HEREDITARY SPHEROCYTOSIS LAB FEATURES
CBC Mild anemia MCV is usually normal (77-87fL) MCH normal MCHC is >36% (This is the only condition in
which an MCHC can be truly increased.) RDW Increased
RBC morphology Spherocyte Varying degrees of polychromasia, anisocytosis
and poikilocytosis
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HEREDITARY SPHEROCYTOSIS LAB FEATURES Bone Marrow
Normoblastic erythroid hyperplasia Increased iron storage
Chemistry Increased
Bilirubin Fecal urobilinogen LD/LDH
Decreased Haptoglobin
Immunohematology DAT negative
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DIAGNOSTIC TESTS FOR HS
Osmotic fragility - ↑ Cells are incubated in decreasing
concentrations of NaCl. Spherocytes lyse sooner than normal red cells.
Autohemolysis test Red cells are incubated at 37A C for 48 hours.
Degree of hemolysis is increased when spherocytes are present.
Red cell membrane studies Membrane proteins are analyzed using gel
electrophoresis.
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TREATMENT OF HS
Splenectomy Corrects for the anemia, but the membrane
defect remains
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DISORDERS
Hereditary elliptocytosis A defect of one of the skeletal proteins Results in the formation of fragile elliptocytic red
cells that are sensitive to mechanical stress. More permeable to Na+
Increased sensitivity to heat Found commonly in Africa and the Mediterranean
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HEREDITARY ELLIPTOCYTOSISCLINICAL FINDINGS
Hemolysis not evident Anemia not characteristic
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HEREDITARY ELLIPTOCYTOSIS LAB FEATURES
CBC Mild anemia Hgb level increased
RBC morphology Elliptocytes or
ovalocytes
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TREATMENT OF HE
Treatment is usually not necessary, but if patients have hemolysis, splenectomy is beneficial.
Condition is not fatal
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DISORDERS
Hereditary pyropoikilocytosis (HPP) Severe subtype of HE Deficiency of α-spectrin and a mutant spectrin
leads to disruption of skeletal lattice and cell destabilization
Cells fragment when heated Tends to affect blacks Presents in infancy or early childhood
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HEREDITARY PYROPOIKILOCYTOSISCLINICAL FINDINGS
Hyperbilirubinemia
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HEREDITARY PYROPOIKILOCYTOSIS LAB FEATURES
CBC MCV decreased (25-55 fL)
RBC morphology Extreme erythrocyte morphologies
Fragments, elliptocytes, triangulocytes etc
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TREATMENT OF HPP
Splenectomy
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DISORDERS
Hereditary Stomatocytosis Syndromes Overhydrated Hereditary Stomatocytosis (OHS)
Permeable to Na+ and K+, cell takes on water Cells resemble stomatocytes
Dehydrated Hereditary Stomatocytosis (DHS) Water content decreased causing cell dehydration so
cells look like targets
No treatment required
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LAB FEATURES
Anemia is mild to moderate Increased bilirubin MCV increased
Stomatocytes: OHS Target cells: DHS
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REFERENES
Harmening, D. M. (2009). Clinical Hematology and Fundamentals of hemostasis (5th ed.). Philadelphia, PA: F.A. Davis Company.
http://laboratorysciencereview.tumblr.com/post/13593250277/elliptocytes
McKenzie, S. B. (2010). Clinical Laboratory Hematology (2nd ed.). Upper Saddle River, NJ: Pearson Education, Inc.
http://tiny.cc/d59xy