MLAB 1415:Hematology Keri Brophy -Martinez
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Transcript of MLAB 1415:Hematology Keri Brophy -Martinez
MLAB 1415:HematologyMLAB 1415:HematologyKeri Brophy-MartinezKeri Brophy-Martinez
Chapter 10:The HemoglobinopathiesPart Two
Hemoglobin C Hemoglobin C DiseaseDisease
IntroductionIntroductionAmino acid substitution of lysine for
glutamic acid at sixth position of Beta chain◦ (α2β2
6Glu-Lys)Is homozygous CC
Chronic hemolytic anemia with associated splenomegaly and abdominal discomfort
Laboratory Findings:Laboratory Findings: Hb C Disease Hb C Disease
Mild to moderate anemia (8-12 g/dL) Retic count 4-8% (slightly increased)
Electrophoresis◦ Most hemoglobin is HbC◦ no HbA present◦ may or may not have increase in Hb F.
Peripheral SmearPeripheral SmearNumerous target
cells, few microspherocytes, schistocytes, and folded cells
May see hexagonal or rod-shaped crystals ("bar of gold”). ◦ Usually intracellular.
Are elongated with blunt ends and parallel sides.
Hemoglobin C Trait (AC)Hemoglobin C Trait (AC)
No symptoms – no anemia. Target cells frequent finding.
Treatment for Hb CTreatment for Hb C
Splenectomy may be beneficial for symptomatic CC homozygous persons.
AC heterozygous persons are
usually asymptomatic, so no treatment required.
Hemoglobin SC Disease Hemoglobin SC Disease HbS gene is inherited from one parent
and HbC gene is inherited from the other parent◦ so both β- chains are abnormal
SplenomegalyPatients can develop vaso-occlusive
crisis
Peripheral SmearPeripheral Smeartarget cellsfolded red cells occasional
glove-shaped intracellular crystals.
Hemoglobin E Hemoglobin E DiseaseDisease
Hb E DiseaseHb E Diseaseβ chain variant – lysine substituted for
glutamic acid in 26th position in beta chain◦ (α2β2
26Glu-Lys) Heterozygous and homozygous
forms. Frequently occurs with Beta
thalassemia No clinical symptoms
Laboratory Findings:Laboratory Findings: Hb E Disease Hb E Disease
Similar to Hb D Mild, microcytic, hypochromic
hemolytic anemia Many target cells Electrophoresis shows E band.
Normal Hb F, no Hb A May protect against malaria
Unstable Unstable Hemoglobin Hemoglobin VariantsVariants
OverviewOverviewUnstable hemoglobins are
hemoglobin variants in which amino acid substitutions or deletions have weakened the binding forces that maintain the structure of the molecule.
Instability may cause Hb to denature and precipitate in the red cells as Heinz bodies.
Overview con’tOverview con’t
Most inherited as autosomal dominant disorders.
When anemia is present, degree of hemolysis varies considerably:◦ Most have mild compensated anemia with
mild reticulocytosis◦ Some have severe, chronic hemolysis with
splenomegaly and jaundice.Hb electrophoresis usually not very
helpful in diagnosis.
Hemoglobin Hemoglobin Variants with Variants with Altered Oxygen Altered Oxygen AffinityAffinity
Methemoglobinemia Methemoglobinemia (Hemoglobin M)(Hemoglobin M)
OverviewOverview
HbM contains ferric iron (Fe3+); Can’t carry oxygen and results in cyanosis.
Three causes of methemoglobinemia:
◦Methemoglobin reductase system Overwhelmed Deficient Molecule is resistant to methemoglobin
reductase
Hb MHb M
5 variants of Hb M which result from single amino acid substitution in the globin chain that stabilizes iron in the ferric form.
Patients have cyanosis, but are otherwise asymptomatic and no treatment is given.
Laboratory Findings in Hb Laboratory Findings in Hb MM
Blood is chocolate brown. Mild hemolytic anemia. Heinz bodies. M band on
electrophoresis.
Hemoglobins with Increased Hemoglobins with Increased Oxygen AffinityOxygen Affinity
Decreased delivery of oxygen to tissues.
Hb values from normal to 20 g/dL. Leukocytes and platelets normal. Normal life span. No treatment. Often results in polycythemia.
Hemoglobins with Decreased Hemoglobins with Decreased Oxygen AffinityOxygen Affinity
Increased release of oxygen to tissues.
Patient may become anemic.
ReferenesReferenesHarmening, 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.
Rodak, B. F. (2002). Hematology Clinical Principles and Applications (3rd ed.). St. Louis: Saunders Elsevier.