Normocytic Anemia Flashcards

1
Q

Cause of aplastic anemia

A

Bone marrow failure due to:

  1. Direct damage (toxic agents, radiation)
  2. Telomere shortening (Dyskeratosis congenita)
  3. Immune-mediated destruction (malaria)
  4. Fanconi’s (congenital)
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2
Q

What is Fanconi’s anemia ?

A
  • X-linked
  • fragile chromosomes
  • predisposed to developing leukemia/ cancer
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3
Q

What is pure red cell aplasia ?

A
  • severe decrease of ONLY erythroid precursors
  • other features of bone marrow are normal
  • acquired or congenital
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4
Q

Aplastic anemia: CBC results (HGB, HCT, RBC, Indices, WBC, PLT, RETIC)

A

HGB decreased
HCT decreased
PLT decreased
WBC decreased
RBC decreased
RETIC decreased

MCV normal or increased
MCH normal
MCHC normal

NOTE: PANCYTOPENIA DUE TO BONE MARROW FAILURE = all CELL LINES DECREASED

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5
Q

Aplastic anemia: BM (M:E, iron stores, characteristic morph)

A
  • M:E; decreased to normal but
    PANCYTOPENIA
  • Iron stores INCREASED
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6
Q

Why is aplastic anemia referred to as a “dry tap” during BM aspirates ?

A

Bone marrow failure = pancytopenia

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7
Q

What is hemolytic anemia ?

A
  • intra or extravascular
  • rate of RBC destruction is GREATER than rate of RBC production
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8
Q

Differentiate intrinsic HA vs extrinsic HA

A

Intrinsic: defect in RBC (membrane, enzymes, hemoglobinopathies, inherited)

Extrinsic: external agents target normal RBCs (immune-mediated, malaria, toxins, mechanical injury)

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9
Q

What are hemoglobinopathies ?

A
  • qualitative or quantitative
  • disorders involving hemoglobin
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10
Q

What are heinz bodies ?

A
  • excess globin chains precipitated into cytoplasm
  • viewed by supravital stains
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11
Q
A
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12
Q
A
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13
Q
A
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14
Q

Cause of Sickle Cell Anemia

A
  • a.a. substitution
  • glutamic acid (negative charge) at POSITION 6 is replaced with VALINE (neutral charge) = conformation change in Hgb
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15
Q

Why does Hgb S form stacks when it releases oxygen ?

A

Hgb S is hydrophobic

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16
Q

List 4 causes of polymerized Hgb

A
  1. Low oxygen
  2. Low pH
  3. Increased 2,3-BPG
  4. Cell dehydration
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17
Q

Why does Hgb S cause clinical complications ?

A
  • oxidative damage to RBC membranes = adherence to capillary surfaces and RBC aggregation = activate coagulation
  • blood becomes more viscous = decreased flow rate
  • surrounding tissues do not get oxygen
  • IVH and EVH due to distorted shape = splenomegaly = more susceptible to infections
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18
Q

Sickle cell Disease (% of HbA, HbA2, HbF, HbS)

A

HbA= NONE
HbA2= N or increased
HbF= <20%
HbS= 80%

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19
Q

Sickle cell Trait (% of HbA, HbA2, HbF, HbS)

A

HbA= >60%
HbA2= N or increased
HbF= <1%
HbS= <40%

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20
Q

Cause of HgC

A
  • glutamic acid at POSITION 6 is replaced by LYSINE in BETA globulin chain
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21
Q

Which Hgb variant forms short and thick crystals under O2 ?

A

HgC for CRYSTALS

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22
Q

Cause and characteristics of HgE

A
  • lysine is replaced at POSITION 26 with GLUTAMIC ACID in the BETA globin chain = 2+ net charge
  • WILL NOT POLYMERIZE
  • commonly inherited with other Hemoglobinopathies (Thalassemia, Hb S or HbSE)
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23
Q

Cause of Hgb M

A
  • proximal/ distal histidine is replaced by TYROSINE = methemoglobin
  • methemoglobin’s FERRIC IRON = ineffective oxygen transport

NOTE: HgM for METHEMOGLOBIN

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24
Q

Significance of G6PD enzyme

A
  • In Embden-Meyerhof pathway (Hexose monophosphate shunt)
  • prevents oxidative damage to RBCs
  • reduces NADP to NADPH to breakdown H2O2 = H2O + O2
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25
Q

How does G6PD cause anemia ?

A
  • Without G6PD in Hexose monophosphate shunt, H2O2 cannot be broken down
  • H2O2 causes oxidative damage to proteins (ie. HEMOGLOBIN) = HEINZ BODIES are precipitated out globin chains
  • increased removal of Heinz bodies by spleen = bite cells + shistocytes
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26
Q

PBS of patient with G6PD Deficiency

A
  • Heinz bodies = precipitated Hgb damaged by H2O2
  • Bite cells + Schistocytes = increased removal of Heinz bodies by spleen
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27
Q

How does Pyruvate Kinase Deficiency cause anemia ?

A
  • PK is an enzyme in Embden-Meyerhof pathway required to produce ATP
  • inadequate ATP = membrane becomes rigid and less deformable, water and potassium leak, and RBCs are removed prematurely (hemolysis)
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28
Q

Cause of hereditary elliptosis

A

Defective SPECTRIN and PROTEIN 4.1 GENES

NOTE: a SPECTRUM is shaped like an ELLIPTO

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29
Q

How does Hereditary elliptocytosis cause anemia ?

A

deformed RBCs become trapped in spleen = EVH HEMOLYSIS

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30
Q

Differentiate the Hereditary elliptocytosis variants

A
  1. Hereditary PYROpoikilocytosis
    - SEVERE
    - increased poikilocytosis
  2. Southeast Asian ovalocytosis
    - Band 3 gene mutations
    - increased rigidity = malaria protection
31
Q

Which Hereditary elliptocytosis variant is “beneficial” ? Which one causes more severe anemia ?

A

Southeast Asian ovalocytes = protects from malaria

Hereditary PYROpoikilocytosis = severe hemolysis (homozygous)

32
Q

Hereditary elliptocytosis variant with Band 3 mutations

A

Southeast Asian ovalocytes

33
Q

Cause of Hereditary Spherocytosis

A

Mutations in VERTICAL transmembrane proteins (Ankyrin, Protein 4.1, band 3, spectrin)

34
Q

How does Hereditary Spherocytosis cause anemia ?

A
  • lack of vertical interactions between transmembrane proteins = spherocytes
  • spleen removes spherocytes = EVH HEMOLYSIS
35
Q

Cause of Hereditary Acanthocytes

A

Mutation in microsomal triglyceride transfer protein (MTP) = increased SPHINGOMYELIN

36
Q

How does Hereditary Acanthocytosis cause anemia ?

A
  • mutations in microsomal triglyceride transfer protein (MTP) = absence of lipids = decreased cholesterol and triglycerides
    - increased sphingomyelin = decreased membrane fluidity = trapped in spleen = EVH

NOTE: cholesterol makes membrane fluid

37
Q

Cause of Paroxysmal Nocturnal Hemoglobinuria

A
  • ACQUIRED mutation of HSC = absence of GPI proteins (CD55 and CD59) = complement activation = IVH

NOTE: GPI proteins prevent cell lysis by complement

38
Q

Function of CD55 on RBCs

A

Prevent lysis from c3 and c5 (complement)
- ABSENT in Paroxysmal Nocturnal Hemoglobinuria

39
Q

Function of CD59 in RBCs

A

Prevent formation of membrane attack complex (MAC) in complement
- ABSENT in Paroxysmal Nocturnal Hemoglobinuria

40
Q

How does DIC cause anemia ?

A
  • systemic fibrin and thrombi formation in micro vasculature
  • coagulation system becomes depleted = organ damage and bleeding
41
Q

MAHAs are characterized by presence of __ on PBS, thrombo__, and loss of RBC through __

A

MAHAs are characterized by presence of SCHISTOCYTES on PBS, thromboPENIA, and loss of RBC through IVH

42
Q

Lab results for DIC

A
  • PBS= schistocytes, thrombocytopenia
  • Fibrinogen= decreased
  • PT and PTT= PROLONGED
  • D-dimers= INCREASED
43
Q

Cause of Thrombotic Thrombocytopenic Purpura

A
  • ADAMTS-13 Deficiency
  • Without ADAMTS-13 to cleave long Von-Willebrand Factor multimers, long VWF readily bind to endothelial cells = PLT binding/ aggregation = thrombin formation = vascular clots
  • RBCs become sheared within vasculature = IVH
  • PLTs are depleted
44
Q

Lab findings for TTP

A
  • PBS = Schistocytes, thrombocytopenia (low PLTs)
  • LDH= INCREASED (IVH)
  • PT and PTT = normal (coagulation factors NOT used up)
45
Q

How does HUS cause anemia ?

A
  • DAMAGES endothelial cells in GASTROINTESTINAL TRACT and KIDNEY = THROMBI FORMATION = IVH

Atypical:
- spontaneous activation of ALTERNATE complement system = vascular injury
- Long vWF multimers released from damaged endothelial cells (without ADAMTS-13 deficiency) = PLT binding/ aggregation & THROMBI FORMATION

46
Q

Cause of HUS

A
  • bacterial Shiga-toxin from Shigella and E. coli O:157
47
Q

Cause of HELLP Syndrome

A

Develop during pregnancies (preeclampsia/ eclampsia)

48
Q

How does HELLP Syndrome cause anemia ?

A
  • Hemolysis, elevated liver enzymes, low platelet counts
  • Due to preeclampsia (in pregnancy) & modified vasculature = leads to endothelial cell dysfunction, damage, activation of PLTs, and thrombi formation = IVH
49
Q

Cause of PNH

A

Paroxysmal Nocturnal Hemoglobinuria:
- red cells are deficient in membrane proteins (CD55, CD59, CD48) due to a lack of the GPI anchor (binds them to the membrane)
- membrane proteins prevent complement = when they are missing, it makes the red cell highly sensitive to hemolysis by complement (IVH)

50
Q

Distinguishing features of plasmodium falciparum

A
  • 1 or more dainty “headphone” rings in a single RBC
  • gametes are yellow “bananas”
51
Q

Immunoglobulin class for: Warm autoimmune anemia

A

IgG

52
Q

Immunoglobulin class for: Cold agglutinin disease

A

IgM

53
Q

Immunoglobulin class for: Paroxysmal cold hemoglobinuria

A

IgG

54
Q

Optimal binding temp: Cold agglutinin disease

A

4°C

55
Q

Optimal binding temp: Paroxysmal cold hemoglobinuria

A

4°C

56
Q

Can Cold agglutinin disease activate complement?

A

Yes

57
Q

Does PCH activate complement?

A

Yes

58
Q

Antibody specificity of PCH

A

Anti-P

59
Q

Which of the following laboratory results are characteristic of hereditary spherocytosis? Select all that apply:

a.
Decreased MCHC

b.
Increased osmotic fragility

c.
Positive DAT

d.
Increased reticulocyte count

A

b.
Increased osmotic fragility

d.
Increased reticulocyte count

60
Q

Which of the following is not a type of microangiopathic hemolytic anemia (MAHA)?

a.
DIC

b.
PCH

c.
HUS

d.
HELLP

A

b.
PCH

61
Q

Which of these is an example of an intrinsic hemolytic disorder? (Select all that apply)

a.
PCH (Paroxysmal cold hemoglobinura)

b.
Microangiopathic hemolytic anemia

c.
PNH (Paroxysmal nocturnal hemoglobinuria)

d.
Malarial infection

A

c.
PNH (Paroxysmal nocturnal hemoglobinuria)

NOTE: intrinsic = defect in RBCs themselves

62
Q

What RBC morphologies are seen in pyruvate kinase deficiency?

a.
Microcytes and elliptocytes

b.
Heinz bodies and spherocytes

c.
Polychromasia

d.
Macrocytes and target cells

A

c.
Polychromasia

63
Q

Acanthocytes are found in association with:

a.
Severe Liver Disease

b.
G6PD Deficiency

c.
PK deficiency

d.
Vitamin B12 deficiency

A

a.
Severe Liver Disease

64
Q

The predominant hemoglobin present in β-thalassemia major is:

a.
Hgb A

b.
Hgb A2

c.
Hgb F

d.
Hgb C

A

c.
Hgb F

65
Q

Which of the following peripheral smear findings is typical of malarial infections?

a.
Spherocytes

b.
Thrombocytopenia

c.
Schistocytes

d.
Polychromasia

A

b.
Thrombocytopenia

66
Q

A positive solubility test is indicative of which hemoglobin variant?

A

HgS; sickle cell

67
Q

All of the following anemias would result in an increased reticulocyte count EXCEPT:

a.
Sideroblastic anemia

b.
Hgb H disease

c.
Hemoglobin C disease

d.
Hereditary spherocytosis

A

a.
Sideroblastic anemia

68
Q

Calculate %parasitemia

A

(number of malaria-infected RBCs in large square) / (~111 RBCs in small square)

69
Q

Buffy coat smears are prepared when..

A
  • Bacteria are seen during PBS examination
  • Per physician request
70
Q

Hemoglobin that is prone to polymerization in alkaline solutions includes (Select all that apply):

a.
Hgb S

b.
Hgb SC

c.
Hgb C

d.
Hgb A2

A

a.
Hgb S

b.
Hgb SC

c.
Hgb C

71
Q

Heinz bodies can be found in:

a.
G6PD deficiency

b.
Pyruvate Kinase deficiency

c.
Hgb S Disease

d.
Hexokinase deficiency

A

a.
G6PD deficiency

72
Q

Spherocytes can be found in (Select all that apply):

a.
G6PD deficiency

b.
Chronic lymphocytic leukemia

c.
Iron deficiency anemia

d.
Aplastic anemia

A

a.
G6PD deficiency

b.
Chronic lymphocytic leukemia

73
Q
  1. A common molecule is implicated in both HUS and TTP. What is this molecule?
  2. How does this molecule contribute to the patient pathology/disease for each disorder?
  3. List two tests that can be used to distinguish HUS from TTP
A
  1. Von Willebrand Factor
    • TTP= an ADAMTS-13 deficiency results in decreased cleaving of VWF multimers. This causes binding of WVF to endothelial cells and activation of thrombi
  • HUS = Shiga-toxin from Shigella or E. coli O:157 cause damage to endothelial cells = vWF is released to cause coagulation (atypical)

3.
- bacterial culture to look for Shigella or E. coli in HUS
- HUS involves kidney damage = creatine clearance can be tested
- PLT count = TTP is much more decreased in comparison to HUS

74
Q

Aplastic Anemia: tests to confirm this diagnosis? What are the expected results?

A
  • CBCD = decreased RBC, Platelets, WBC, reticulocytes
  • PBS= pancytopenia
  • Bone marrow biopsy* = fat
  • Molecular testing = see if patient is genetically predisposed to get aplastic anemia

*NOTE= since aspirate is a dry tap