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01 Hematology > Hemolytic Anemias and Inherited Erythrocyte Disorders > Flashcards

Hemolytic Anemias and Inherited Erythrocyte Disorders Flashcards

1
Q

What are the general characteristics of hemolytic anemia?

A

RBC destruction, shortened RBC survival, increased erthyropoietin, increased bone marrow RBC production , and accumulation of RBC breakdown products

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2
Q

What is the average lifespan of an RBC?

A

120 days

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3
Q

What are the classifications of hemolytic anemia based on sites of hemolysis?

A

Intravascular and extravascular

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4
Q

Where does extravascular hemolytic anemia take place?

A

Phagocytosis of erythrocytes by macrophages within the spleen, liver, and bone marrow

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5
Q

What are the general mechanisms of intravascular hemolysis?

A

Immune-mediated, toxins or pathogens, mechanical damage

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6
Q

What happens to Hb once it is released from a hemolyzed RBC?

A

It is bound to haptoglobin and te complex is metabolized by the reticuloenothelial system

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7
Q

Beside Hb, what measurable protein is released from destroyed RBCs?

A

Lactate Dehydrogenase

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8
Q

How does hemolytic anemia affect levels of free haptoglobin?

A

Free haptoglobin decreases

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9
Q

What is hemoglobinemia?

A

The presence of Hb-dimers due to a concentration of free Hb that exceeds the saturation of haptoglobin

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10
Q

How is heme eliminated from the body?

A

The spleen reticuloendothelial cells break down heme into indirect (unconjugated bilirubin, which is conjugated in the liver and excreted in urine and feces

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11
Q

True or False: Unconjugated bilirubin is an abnormal lab finding?

A

True

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12
Q

What is the lab evidence of intravascular hemolysis?

A

Schistocytes, agglutination, increased lactate dehydrogenase, decreased haptoglobin, increased free Hb, increased urine Hb or hemosiderin

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13
Q

What is the lab evidence of extravascular hemolysis?

A

Microspherocytes, slightly increased lactate dehydrogenase, slightly decreased haptoglobin, increased indirect bilirubin, increased urine and fecal urobilinogen, and splenomegaly

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14
Q

True or False: Specific cases of hemolytic anemia will almost always be either intravascular hemolysis or extravascular hemolysis.

A

False- Many (if not most cases) of hemolytic anemia have a mix of intravascular and extravascular hemolysis with one or the other predominating

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15
Q

What are the classifications of hemolytic anemia based on the cause of hemolysis?

A

Intrinsic (Intracorpuscular) or Extrinsic (extracorpuscular)

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16
Q

What are the four major categories of intrinsic RBC defects?

A

Hemoglobin structure abnormalities, hemoglobin synthesis abnormalities, erythrocyte membrane abnormalities, and erythrocyte enzyme abnormalities

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17
Q

How many heme groups are in one hemoglobin molecule?

A

4

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18
Q

What is heme?

A

Iron and protoporphyrin

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19
Q

What is the form of the majority of the body’s iron?

A

hemoglobin

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20
Q

What is the site of heme synthesis?

A

Predominantly in erythroid precursors of bone marrow

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21
Q

What type(s) of globin make up normal adult Hb?

A

Alpha and beta

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22
Q

Where is globin synthesized?

A

The cytoplasm of normoblasts and reticulocytes

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23
Q

What are the three major type of human hemoglobins and what is their typical relative amounts in the adult body?

A

Hb A (97%), Hb A2 (2%), and Hb F (1%)

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24
Q

What globin chains make up each major type of Hb?

A

HbA= 2 alpha 2 beta; HbA2= 2 alpha 2 delta; HbF= 2 alpha 2 gamma

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25
Q

In what conditions is the amount of HbF increased?

A

Beta thalassemia, sickle cell anemia, hydroxyurea treatment

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26
Q

In what conditions is the amount of Hb A2 increased? Decreased?

A

Beta thalassemia, megaloblastic anemia; Fe deficiency, sideroblastic anemia

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27
Q

What is methemoglobin?

A

A hemoglobin molecule in which one or more of the iron atoms are in the ferric state

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28
Q

What enzyme keeps the formation of methemoglobin at bay?

A

NADH-dependent cytochrome b5-methemoglobin reductase

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29
Q

What is methemoglobinemia and how does it present?

A

Increased concentration of methemoglobin; cyanosis

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30
Q

What is the basis of inherited methemoglobinemia?

A

Defects in genes that regulate production of cytochrome b5 reductase or defects in Hb structure (HbM)

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31
Q

What are the acquired causes of methemoglobinemia?

A

Oxidant drugs or environmental oxidant chemicals

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32
Q

What are hemoglobinopathies?

A

Structural abnormalities of Hb that lead to a clinical manifestation

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33
Q

Abnormalities of what hemoglobin change that cause hemoglobinopathies often occur in which chain?

A

Beta

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34
Q

What forms of Hb are due to beta hemoglobinopathies?

A

Hb S, C, D, and E

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35
Q

What are the two major types of Hb electrophoresis? Which can each be used for?

A

Alkaline (differentiates HbA2, S, F, and A) and acid (HbC from A2)

36
Q

What is the mechanism of Sickle Cell Disease inheritance?

A

Autosomal recessive

37
Q

What is the cause of sickle cell disease?

A

A single substitution of valine for glutamate in the 6th position of the beta Hb chain

38
Q

What is the average life span of a sickle cell?

A

5-20 days

39
Q

When do symptoms of sickle cell anemia typically manifest?

A

~3-6 months old

40
Q

To what kind of infection are sickle cell disease patients more susceptible to and why?

A

Susceptible to infections by encapsulated bacteria because they have an abnormal spleen that undergoes autosplenectomy by 8 or 9 yrs old

41
Q

What is an aplastic crisis and what is a common cause in HbSS?

A

Occurs when patients cannot produce enough RBCs to keep up with hemolysis– commonly due to parvovirus

42
Q

What is a Pain crisis? What are the precipitating factors?

A

A painful event that happens in sickle cell patients due to vaso-occlusive events; Hypoxia, Acidosis, Fever, Infection, Dehydration, Exposure to cold

43
Q

What is Hand-Foot Syndrome?

A

Ischemic necrosis of small tubular bones causing bilateral painful swelling of dorsa of hands and feet in young sickle cell patients

44
Q

What is an acute splenic sequestration crisis?

A

Sudden pooling of blood in the spleen due to acute circulatory obstruction by sickle cells in spleen causing severe anemia and hypovolemic shock because so much blood is sequestered in the spleen

45
Q

What renal problems are commonly associated with Sickle Cell disease?

A

Inability to produce concentrated urine, painless hematuria, nephrotic syndrome and increased incidence of UTIs

46
Q

What is acute chest syndrome?

A

Vascular occlusions in the pulmonary vessels (of HbSS pts)

47
Q

What comprises the stones that often cause cholelithiasis in pts with hemolytic disorders?

A

Calcium bilirubinate

48
Q

What abnormal CBC results would a sickle cell patient have?

A

Normocytic, normochromic anemia, reticulocytosis, increased RDW, and often neutrophilia and thrombocytosis

49
Q

What abnormal findings would be seen on the PBS of a sickle cell disease pt. ?

A

Sickle cells, target cells, nRBCs, Howell-Jolly bodies and pappenheimer bodies

50
Q

What abnormal lab results would be seen in a sickle cell diseased patient?

A

Hyperbilirubinemia, decreased haptoglobin, increased LDH

51
Q

What are the treatments for sickle cell disease?

A

Frequent RBC transfusions, hydroxyurea or nitric oxide treatment, and in severe cases, hematopoietic stem cell transplant

52
Q

What is the most common hemoglobinopathy in the US?

A

Sickle Cell Trait

53
Q

What is the genetic difference between HbS and HbC?

A

The normal glutamate at the 6th position of the beta chain is exchanged for a valine in HbS and lysine in HbC

54
Q

What abnormal cell can often be found on the PBS of a pt with Hemoglobin C disease?

A

Target cells

55
Q

What abnormal accumulation is seen in Hemoglobin C disease patient smears?

A

Hexagonal or rod-shaped crystals made of condensed HbC

56
Q

What is the severity of HbSC disease relative to HbSS and HbAS?

A

SC is somewhere between SS and AS

57
Q

What are thalassemias?

A

A group of hereditary disorders in which there is absent or decreased synthesis of one or more of the normal polypeptide chains of hemoglobin

58
Q

What is alpha thalassemia?

A

Condition in which alpha Hb chain synthesis is absent or diminised usually due to deletion of one or more alpha genes

59
Q

What kind of Hb forms are decreased in alpha thalassemia?

A

All- HbA, A2, and F

60
Q

What is minor alpha thalassemia?

A

Alpha thalassemia with the loss of two alpha genes

61
Q

What are the abnormal CBC results of a patient with alpha thalassemia?

A

Mild microcytic anemia, normal-increased RBC count

62
Q

What is HbH disease

A

Alpha thalassemia with absence of 3/4 alpha chain genes such that HbH (beta chain tetramers) are formed

63
Q

How does HbH disease present?

A

Moderate to severe microcytic anemia and splenomegaly

64
Q

True or False: Hb Electrophoresis can be used to diagnose HbH disease

A

True

65
Q

How does alpha thalassemia with 4 deleted alpha chain genes deleted present?

A

Hydrops fetalis (death)

66
Q

What is Bart’s Hb?

A

Tetramers of gamma globulin chains seen in pts with absence of all four alpha chain genes

67
Q

What genetic alteration is most commonly the cause of beta thalassemias?

A

Point mutations within the beta chain gene

68
Q

What is the mechanism of beta thalassemia inheritance?

A

Autosomal dominant

69
Q

What are the three types of beta thalassemia?

A

B-thalassemia minor, b-t intermedia, b-t major (cooley’s)

70
Q

What is the genotype that causes beta thalassemia minor?

A

One normal and one mutated (either diminished or absent)

71
Q

True or false: All thalassemias give rise to microcytic anemias.

A

True

72
Q

What are the abnormal laboratory findings seen with beta thalassemia minor?

A

Low Hb/HCT; Microcytosis; normal- elevated RBC; mild hypochromia; target cells, basophilic stippling, and increases in HbF and or HbA2

73
Q

What is the hallmark findings of beta thalassemia trait?

A

Increase in RBC in the presence of decreased MCV

74
Q

What is the genotype of a patient with beta thalassemia intermedia? Which is more severe

A

Bo/B+ (more severe) or B+/B+

75
Q

What laboratory findings are seen in bTHalassemia intermedia that aren’t in BT minor?

A

Hemolytic anemia, hypochromia, increased RDW, and nRBCs

76
Q

What are the clinical manifestations of BT major?

A

Skeletal deformations, dilated cardiomyopathy secondary to severe anemia, growth and development delayed, hepatosplenomegaly,

77
Q

How can sickle cell beta thalassemia be differentiated from just sickle cell trait?

A

Patients with just sickle cell will have more HbA than HbS; Pts with BT sickle cell have more HbS than HbA

78
Q

What is the most common RBC membrane defect?

A

Hereditary Spherocytosis

79
Q

What is the morphology of a spherocyte?

A

Round cells slightly larger than RBCs with NO central pallor

80
Q

What is the most common principle defect that results in spherocyte formation?

A

Abnormality of membrane protein ankyrin

81
Q

What CBC finding is most characteristic of hereditary spherocytosis?

A

Increased MCHC

82
Q

What are the two major conditions that present with spherocytosis and what test can be used to differentiate them?

A

Hereditary Spherocytosis or autoimmune hemolytic anemia; Direct anti-globulin (Coomb’s test)

83
Q

What is the second most common RBC membrane defect?

A

Hereditary Elliptocytosis

84
Q

What is the most common cause of hereditary elliptocytosis?

A

Abnormalities of spectrins that result in their inability to form multimers

85
Q

What is the cause of the most common type of hereditary stomatocytosis?

A

Abnormal stomatin protein

86
Q

What is paroxysmal nocturnal hemoglobinuria?

A

An acquired intrinsic stem cell disorder (membrane defect) in the marrow making RBCs abnormally sensitive to complement mediated lysis

87
Q

What is the common abnormality in PNH cases?

A

Genetic mutation leading to the inability of cells to synthesize the glycosyl-phosphatidyl inositol anchor that binds various complement regulating proteins that protein RBCs from complement binding

01 Hematology (16 decks)

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