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MLAB 1415: Hematology Keri Brophy- M artinez. Chapter 15: Hemolytic Anemias Membrane Defects Part Two. Disorders. Membrane lipid disorders RBCs can acquire lipids when plasma lipid increase Results in expansion of membrane and formation of abnormal shapes Acanthocytosis Spur cell anemia
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MLAB 1415: HematologyKeri Brophy-Martinez Chapter 15: Hemolytic Anemias Membrane Defects Part Two
Disorders • Membrane lipid disorders • RBCs can acquire lipids when plasma lipid increase • Results in expansion of membrane and formation of abnormal shapes • Acanthocytosis • Spur cell anemia • Abetalipoproteinemia
Disorders • Paroxysmal nocturnal hemoglobinuria (PNH) • Acquired intravascular hemolytic anemia characterized by intermittent (paroxysmal) sleep-associated (nocturnal) blood in the urine (hemoglobinurea). • Onset is gradual ocurring mostly in middle-aged adults of either gender.
Etiology • Stem cell mutation leading to abnormal clones of differentiated hematopoietic cells. • These clones bind complement • At least 9 cell surface proteins that regulate complement are missing. As a result, the red cell membrane is markedly sensitive to complement. • Complement is a series of proteins circulating in the blood which, when activated, can cause disruption of cell membranes (RBC and microorganisms)
Clinical features • Hemoglobinurea in first morning specimen • Hemosidinurea • Chronic anemia • Infections • Thrombosis • 5-10% of cases will convert to acute myelogenous leukemia; 25% will convert to aplastic anemia.
Lab Features: PNH • Hgb: 8-10 g/dL • Leukopenia • Thrombocytopenia • PB • Normocytic or macrocytic • If IDA develops: Hypochromic, microcytic • nRBCS
Diagnostic laboratory tests • Screening test: Sugar water test • Blood is incubated in a solution of sugar water. The low ionic strength of the solution activates complement and PNH cells are lysed. • Confirmation test: Ham’s Test (Acidified Serum Lysis Test) • PNH cells incubated in acidified serum will lyse whereas normal cells will not lyse. In order to be called positive, two conditions must be met: 1) Hemolysis occurs with the patient’s cells and not with normal cells, 2) hemolysis is enhanced by acidified serum and does not occur with heat activated serum in which complement has been destroyed. • Flow cytometry • More sensitive and specific than above tests • Immunophenptype of RBC
Therapy • Therapy is directed at the complications that arise from infections, anemia and thromboses. • Anemia - iron therapy or transfusion if severe enough • Hemolytic episodes - corticosteroid therapy to stimulate erythropoiesis • Thromboses - anticoagulant therapy • Bone marrow transplant if • Aplasia exists • Patient younger than 50
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