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Clinical Hematology > Test 5 Review sheet > Flashcards

Test 5 Review sheet Flashcards

1
Q

What type of effects/defects are present in qualitative hemoglobinopathies?

A

Structural defects

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2
Q

What condition is the most common form of hemoglobinopathies?

A

Sickle cell diseases

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3
Q

What is Vasoocclusive event

A

hallmark features of sickle cell disease, accounting for most hospital and emergency department visits

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4
Q

What ethnic group doesn’t express sickle cell diseases?

A

Scandinavia

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5
Q

Factors that make blood more viscous?

A

when polymers are formed and sickle cells are created

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6
Q

What is the effect of blood viscosity

A

reduced blood flow

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7
Q

How does blood become acidic?

A

prolongs exposure of the sickle cells to a hypoxic environment (decreased oxygen tension)

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8
Q

What occurs post-reduction of pH?

A

reduction in pH occurs and 2,3-biphosphoglycerate levels

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9
Q

Characterize sickle cell crisis in a blood smear

A

target cells, Howell-Jolly bodies, and an elevated white count (leukocytosis)

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10
Q

What confers resistance against P. Falciparum?

A

Sickle cell trait (heterozygosity for hemoglobin S [Hb S])

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11
Q

Where is this abnormal hemoglobin prevelant?

A

areas where this form of malaria is endemic

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12
Q

What globin genes are abnormal in homozygous Hb S?

A

Beta-globin genes are abnormal in homozygous Hb S. Hb A is not present unless the patient has received a red cell transfusion

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13
Q

Characterize Hb S to Hb A

A

Hb S is less soluble than normal Hb A, the reticulocyte count is elevated, and patients usually have a high Hb F

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14
Q

What is the tube solubility test of Sickle cell trait and Hb SS

A

The tube solubility test is positive

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15
Q

How can you differentiate b/n sickle cell trait and sickle cell anemia?

A

hemoglobin electrophoresis is the best test to differentiate the 2
. Sickle cell trait should have roughly 40% Hb S and 55% Hb A
sickle cell anemia should have predominantly Hb S with a variably increased Hb F and no Hb A

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16
Q

What other hemoglobin can appear on an alkaline hemoglobin electrophoresis?

A

Hb D

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17
Q

What would precipitate sickling of sickle cell anemia?

A

Hb S forms insoluble polymers when the oxygen saturation is low

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18
Q

What red cell morphology is present in sickle cell trait?

A

Target cells are present

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19
Q

What conditions show target cells? what conditions don’t?

A

They are present in Hb C, Hb E, and sickle cell. not seen in hereditary spherocytosis

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20
Q

The presence of what hemoglobin gives a positive tube solubility?

A

presence of Hb S

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21
Q

What hemoglobin type is elevated in Hb M?

A

Methemoglobin is elevated, 30% to 50% methemoglobin (Fe3+)

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22
Q

What may be present but not visible in Hb M?

A

Heinz bodies may be present, but they are not visible with a Wright stain

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23
Q

How is methemoglobin formed?

A

The amino acid substitutions found in the various Hb Ms cause heme iron to autooxidize, forming methemoglobin

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24
Q

How are Heinz bodies formed?

A

when hemoglobin is unstable and precipitates

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25
Q

What occurs during hemoglobin O2 high affinity?

A

less oxygen is released to tissue, leads to increase erythropoietin and make more red cells

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26
Q

Characterize point mutation

A

Replacement of one nucleotide in the normal gene with a different nucleotide

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27
Q

How can point mutation affect the protein’s function?

A

results in a different amino acid and can affect the protein’s function

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28
Q

Which hemoglobin are seen on cellulose acetate?

A

Hb S, Hb A, Hb F, and Hb A2

29
Q

Where do you see Hb A?

A

transfused red cells

30
Q

What are Hb A2 and F

A

normal hemoglobins

31
Q

Where do you see Hb S

A

patients with homozygous Hb S

32
Q

In what ethnicity can you find Hb E?

A

Southeast Asian populations

33
Q

What are the lab results for Hb E?

A

migrates with Hb C on cellulose acetate alkaline electrophoresis.
The MCV is low and target cells are present in this trait
Because Hb A is also present, this patient probably has Hb E trait

34
Q

What is thalassemia?

A

a varied group of disorders in which the synthesis of a normal globin chain is reduced or absent.
globin chains that are made are normal in amino acid structure

35
Q

What are the concentrations of hemoglobins and what kind of globin chains are they made of?

A

Hb A: 96%, made of a2b2
Hb A2: 2%, made of a2d2
Hb F: 2%, a2g2

36
Q

What globin chains is deficient/absent in beta thalassemia?

A

Beta globin chain is decreased to absent

37
Q

What globin chain is normal in beta thalassemia?

A

alpha globin chain synthesis is normal

38
Q

What population doesn’t require beta chains?

A

Infants up until approximately 6 months of age have an elevated Hb F that does not require beta chains

39
Q

What is the primary mechanism that leads to anemia in thalassemia?

A

An imbalance exists in the rate of globin chain synthesis in the thalassemias

40
Q

what damages the red cell?

A

A build-up of the globin chain is produced in excess

41
Q

Characterize the bone marrow in thalassemia

A

Erythroid hyperplasia is present

42
Q

What group of disorders are thalassemia?

A

a heterogeneous group of disorders that range from asymptomatic (benign) to death (incompatible with life)

43
Q

State the morphology of RBCs in beta thalassemia major and minor

A

Minor: Basophilic stippling is seen in red cell
Major: Microcytes, hypochromia, and target cells (however present in minor as well)

44
Q

What can differentiate beta thalassemia major and minor?

A

Clinical findings, hemoglobin concentration, and presence of Hb A

45
Q

What is the primary hemoglobin in homozygous beta-thalassemia?

A

Hb F, with the remainder being Hb A2.

46
Q

What hemoglobin is not present in homozygous beta-thalassemia?

A

Hb A exists, because no beta globin chains are made

47
Q

What cannot be produced with missing alpha globin chains?

A

Hb F

48
Q

What hemoglobin is present at birth in all forms of alpha thalassemia?

A

Barts (gamma 4) hemoglobin is present at birth

49
Q

What is not present in all forms of alpha thalassemia?

A

Hb H inclusions, anemia, and microcytic red cells

50
Q

How does hemoglobin H disease occur?

A

three genes are missing for alpha globin chain synthesis
excess of beta chains (b4), which is named Hb H, is present and easily detectable

51
Q

What kind of anemia is present with Hb H disease?

A

mild to moderate anemia

52
Q

In what ethnicity is Hb H disease prevelent?

A

Asian ethnicity

53
Q

What hemoglobin require alpha chains?

A

All normal hemoglobins (A, A2, and F)

54
Q

What is the predominant hemoglobin in the uterus?

A

the predominant hemoglobin will be Hb Barts (g4)

55
Q

Characterize Hb Barts?

A

a high-oxygen-affinity hemoglobin and thus is not effective in reversible oxygen transport

56
Q

What is the predominant hemoglobin up until the 3rd trimester?

A

Hb Portland is the primary hemoglobin

57
Q

Characterize a patient with hemoglobinopathy for Hb S?

A

patient will not have any normal beta chains to combine with alpha chains and form Hb A
patient will have primarily Hb S, with an elevated Hb F, which is the same pattern seen in homozygous Hb S (i.e., sickle cell anemia)
red cells will be microcytic

58
Q

What tests are useful for differentiating thalassemia?

A

Hemoglobin electrophoresis
CBC results and clinical findings (could vary)

59
Q

What is the CBC result for a thalassemia trait?

A

The red blood cell (RBC) count is relatively high with a low MCV in thalassemia trait

60
Q

What is the iron deficiency result for a thalassemia trait?

A

MCV can be low, but the red count is also low

61
Q

Characterize Hb Barts

A

composed of four gamma chains
It is present at birth in all forms of alpha-thalassemia, even the silent carrier state (one gene deletion)

62
Q

The Beta+ gene locus decreases what?

A

beta Globin chain synthesis is decreased

63
Q

What is the treatment for patients with beta thalassemia major?

A

massive red cell transfusion therapy

64
Q

What is the consequence for treatment of beta thalassemia major?

A

build up of iron in the body from all the transfused RBCs because the body has no mechanism for excreting iron

65
Q

Characterize Hb Lepore

A

delta-beta fusion globin chain with decreased synthesis of the chain
Heterozygotes have a clinical course similar to that of beta-thalassemia minor.

66
Q

In which ethnicity is Hb E prevalent?

A

Southeast Asia

67
Q

Why is seperating Hb A2 and Hb F important

A

important to do when working up patients with possible thalassemic syndromes

68
Q

What test is able to separate and quantify Hb A2 and Hb F?

A

High-performance liquid chromatography

Clinical Hematology (6 decks)

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