HEMA LEC - Hemolytic Anemias due to Intrinsic defects Flashcards Preview

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Flashcards in HEMA LEC - Hemolytic Anemias due to Intrinsic defects Deck (29):
1

a. Characterized by a sudden loss of blood resulting from trauma or other severe forms of injury


Acute blood loss anemia

2

b. Clinical symptoms: Hypovolemia, rapid pulse, low blood pressure, pallor

Acute blood loss anemia

3

. Laboratory: Normocytic/normochromic anemia; initially normal reticulocyte count, hemoglobin/ haematocrit; in a few hours, increase in platelet count and leukocytosis with a left shift, drop in hemoglobin/hematocrit and RBC; reticulocytosis in 3-5 days

Acute blood loss anemia

4


a. Characterized by a gradual, long-term loss of blood; often caused by gastrointestinal bleeding

Chronic blood loss anemia

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b. Laboratory: Initially normocytic/ normochromic anemia that overtime causes a decrease in hemoglobin/ haematocrit; gradual loss of iron causes microcytic/hypochromic anemia

Chronic blood loss anemia

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All cause a normocytic/normochromic anemia usually hereditary with reticulocytosis due to accelerated destruction.

hemolytic anemias due to intrinsic defects

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Most common membrane defect; autosomal dominant; characterized by splenomegaly, variable degree of anemia, spherocytes on the peripheral blood smear.


hereditary spherocytosis

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b. Increased permeability of the membrane to sodium.

hereditary spherocytosis

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c. Results in loss of membrane fragments; erythrocytes have DECREASED SURFACE-TO-VOLUME RATIO; rigid spherocytes culled/ removed by splenic macrophages.

hereditary spherocytosis

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d. Laboratory: Spherocytes, MCHC may be > 37g/dL, increased OSMOTIC FRAGILITY AND INCREASED SERUM BILIRUBIN

hereditary spherocytosis

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a. Autosomal dominant; most persons asymptomatic due to normal erythrocyte life span; > 25% ovalocytes on the peripheral blood smear

Hereditary elliptocytosis (ovalocytosis)

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b. Membrane defect is caused by polarization of cholesterol at the ends of the cell rather than around pallor area.

Hereditary elliptocytosis (ovalocytosis)

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a. Autosomal dominant; variable degree of anemia; up to 50% stomatocytes on the blood smear.

Hereditary stomatocytosis

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b. Membrane defect due to abnormal permeability to both sodium and potassium; causes erythrocyte swelling

Hereditary stomatocytosis

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a. Autosomal recessive; mild anemia associated with steatorrhea, neurological and retinal abnormalities; 50-100% of erythrocytes are acanthocytes.

Hereditary acanthocytosis (abetalipoproteinemia)

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b. Increased cholesterol: lecithin ratio in the membrane due to abnormal plasma lipid concentrations; absence of serum B-lipoprotein needed for lipid transport.

Hereditary acanthocytosis (abetalipoproteinemia)

17

a. Sex-linked enzyme defect; most common enzyme deficiency in the hexose monophosphate shunt

d. Usually, not anemic until oxidatively challenged (primaquine, sulfa drugs); then severe haemolytic anemia with reticulocytosis.

G6PD (glucose-6-phosphate dehydrogenase) deficiency

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c. Results in oxidation of hemoglobin to methemeglobin (Fe3+); denatures to from Heinz bodies.

G6PD (glucose-6-phosphate dehydrogenase) deficiency

19

b. Reduced glutathione levels are not maintained because of decreased NADPH generation.

G6PD (glucose-6-phosphate dehydrogenase) deficiency

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a. Autosomal recessive; most common enzyme deficiency in Embden-Meyerhof pathway

Pyruvate kinase (PK) deficiency

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b. Lack of ATP causes impairment of the cation pump that controls intracellular sodium and potassium levels.

Pyruvate kinase (PK) deficiency

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c. Decreased erythrocyte deformability reduces their life span.

Pyruvate kinase (PK) deficiency

23

d. Severe haemolytic anemia with reticulocytosis and echinocytes.

Pyruvate kinase (PK) deficiency

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a. An acquired membrane defect in which the red cell membrane has an increased sensitivity for complement binding as compared to normal erythrocytes
b. Etiology unknown



Paroxysmal nocturnal hemoglobinuria (PNH)

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c. All cells are abnormally sensitive to lysis by complement.

Paroxysmal nocturnal hemoglobinuria (PNH)

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e. Although Ham’s and sugar water tests have been traditionally used in diagnosis of PNH, the standard now used is flow cytometry to detect deficiencies for surface expression of glycosyl phosphatidylinositol (GPI) – linked proteins such as CD55 and CD59.

Paroxysmal nocturnal hemoglobinuria (PNH)

27

d. Characterized by: Pancytopenia; chronic intravascular hemolysis causes hemoglobinuria and hemosiderinuria at an acid pH at night; PNH noted for low leukocyte alkaline phosphatase (LAP) score; Ham’s and sugar water tests used in diagnosis; increased incidence of acute leukemia.

Paroxysmal nocturnal hemoglobinuria (PNH)

28

traditional method of diagnosing PNH

Ham’s and sugar water tests

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Standard method of diagnosing PNH

flow cytometry

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