1 / 21

MLAB 1415: Hematology Keri Brophy-Martinez

MLAB 1415: Hematology Keri Brophy-Martinez. Chapter 15: Hemolytic Anemia: Membrane Defects. Introduction. Defects due to abnormalities in membrane proteins or lipids Defects alter membrane’s stability, shape, deformability and permeability Hemolysis occurs extravascularly .

quincy
Download Presentation

MLAB 1415: Hematology Keri Brophy-Martinez

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. MLAB 1415: HematologyKeri Brophy-Martinez Chapter 15: Hemolytic Anemia: Membrane Defects

  2. Introduction • Defects due to abnormalities in membrane proteins or lipids • Defects alter membrane’s stability, shape, deformability and permeability • Hemolysis occurs extravascularly

  3. 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

  4. Conditions Associated with Membrane Defects • Hereditary spherocytosis • Hereditary elliptocytocytosis • Hereditary pyropoikilocytosis • Overhydrated and dehydrated hereditary stomatocytosis • Membrane lipid disorders • Paroxysymalnocturalhemoglobinuria

  5. 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

  6. Clinical Findings • Varies in severity • Compensated hemolytic disease • No anemia • Intermittent jaundice • Splenomegaly • Cholelithiasis: pigment bile stones from increased bilirubin breakdown

  7. 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.) • RBC morphology • Spherocyte • Varying degrees of polychromasia, anisocytosis and poikilocytosis

  8. Lab Features • Bone Marrow • Normoblastic erythroid hyperplasia • Increased iron storage • Chemistry • Increased • Bilirubin • Fecal urobilinogen • LD • Decreased • Haptoglobin • Immunohematology • DAT negative

  9. 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 37̊ C for 48 hours. Degree of hemolysis is increased when spherocytes are present. • Red cell membrane studies • Membrane proteins are analyzed using gel electrophoresis.

  10. Treatment of HS • Splenectomy • Corrects for the anemia, but the membrane defect remains

  11. 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+ • Tends to affect blacks, especially in Africa

  12. Clinical findings • Hemolysis not evident • Anemia not characteristic

  13. Lab Features • CBC • Mild anemia • Hgb level increased • RBC morphology • Elliptocytes or ovalocytes

  14. Treatment of HE • Treatment is usually not necessary, but if patients have hemolysis, splenectomy is beneficial.

  15. 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

  16. Clinical Findings • Hyperbilirubinemia

  17. Lab Features • CBC • MCV decreased (25-55 fL) • RBC morphology • Extreme erythrocyte morphologies • Fragments, elliptocytes, triangulocytes etc

  18. Treatment of HPP • Splenectomy

  19. 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

  20. Lab Features • Anemia is mild to moderate • Increased bilirubin • MCV increased • Stomatocytes: OHS • Target cells: DHS

  21. Referenes • Harmening, D. M. (2009). Clinical Hematology and Fundamentals of hemostasis (5th ed.). Philadelphia, PA: F.A. Davis Company. • McKenzie, S. B. (2010). Clinical Laboratory Hematology (2nd ed.). Upper Saddle River, NJ: Pearson Education, Inc. • http://tiny.cc/d59xy

More Related