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SBL > Pathology of Red Blood Cells and Bleeding Disorders (Part 1 of 3) > Flashcards

Pathology of Red Blood Cells and Bleeding Disorders (Part 1 of 3) Flashcards

1
Q

What is hemoglobin?

A

the main protein in the RBC, transports oxygen and carbon dioxide

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2
Q

what is hematocrit?

A

percentage of whole blood volume occupied by red cells

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3
Q

How do you calculate MCV?

A

HCT/RBC

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4
Q

how do you calculate MCH?

A

hgb/rbc

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5
Q

how do you calculate MCHC?

A

hgb/hct

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6
Q

what type of anemia is indicated if there is a low MCV?

A

microcytic

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7
Q

what type of anemia is indicated if there is a high MCV?

A

macrocytic

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8
Q

what type of anemia is indicated if there is a low MCH?

A

hypochromic

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9
Q

how do reticulocytes appear in a peripheral blood smear? and what stain can you use to highlight the presence of the RNA in the reticulocytes?

A

reticulocytes appear polychromatic with a purple grey tinge in larger cells; a supravital stain can be used

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10
Q

What does the RDW tell us?

A

it is a measure of the variability in size of circulating erythrocytes

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11
Q

what is the term used for increased variability in size of cell?

A

anisocytosis

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12
Q

How does anemia manifest in acute blood lost?

A

through low HGB/HCT 6-12 hours later; there will be a normal MCV/MCH; initially the retic count will stay low, and then 6-7 days later it will rise to compensate for anemia

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13
Q

When does chronic blood lose lead to anemia?

A

when the rate of loss exceeds the rate of replacement

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14
Q

what type of anemia will present with chronic blood loss?

A

iron deficiency anemia

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15
Q

What are the two common themes seen with hemolytic anemias?

A

peripheral destruction is the basis for anemia and the bone marrow will attempt to compensate

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16
Q

what is the main effect of hereditary spherocytosis?

A

mutations lead to unstable skeletal membrane proteins- so you don’t have stability in the membrane, and as cells are released into the circulation, little pieces get lost over time and as a result the cell has to contract down to form a sphere

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17
Q

what happens to the RBCs in hereditary spherocytosis when they go through the microvasculature of the spleen?

A

the spherocytes are destroyed because they have lost their ability to deform and move through that microvasculature

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18
Q

the spherocytes moving through the spleen results in what?

A

splenomegaly–> hypersplenism

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19
Q

In hereditary spherocytosis, a common treatment is to remove the patient’s spleen. Patients without a spleen typically have what in their RBCs?

A

they have increased “howell Jolly bodies”, which are just DNA inclusions that are typically removed by the spleen

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20
Q

what does the anemia of a patient with hereditary spherocytosis look like? (i.e. MCV, MCH, and MCHC)

A

MCV= decreased, MCH= same, and MCHC= increased

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21
Q

what is the typical presentation of a patient with hereditary spherocytosis? (3)

A

anemia, jaundice, and splenomegaly

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22
Q

what can parvovirus infection lead to in anyone with a hemolytic anemia?

A

an aplastic crisis with overdependence on erythropoiesis

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23
Q

what occurs in a parvovirus B19 infection?

A

there is destruction of erythroid precursors in the bone marrow

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24
Q

what is the inheritance pattern of G-6-PD deficiency?

A

x-linked recessive

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25
Q

what demographic is G-6-PD very common in?

A

sub-saharan africa, middle east, and mediterranean

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26
Q

under what conditions can we peroxidase free radicals?

A

whenever we have enough reduced glutathione

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27
Q

In order to have enough reduced glutathione, what must we have?

A

an electron from NADPH

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28
Q

what is the role of G6PD?

A

it must replace the electron lost from NADPH

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29
Q

When does G-6-PD deficiency present?

A

it is marked by episodic hemolysis due to oxidative stress–> certain drugs, stress, infection, and select foods such as fava beans

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30
Q

What does oxidative damage cause?

A

denaturation and precipitation of hemoglobin and other stromal proteins known as Heinz bodies

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31
Q

what happens to the cells with Heinz bodies?

A

they are less able to traverse the splenic red pulp and may be eliminated- bite cells are where the spleen has removed them

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32
Q

people with the G6PD deficiency actually have an advantage when exposed to what?

A

plasmodium falciparum

33
Q

what is sickle cell anemia?

A

a mutation in the beta chain of hemoglobin can result in variant hemoglobins- like Hgb S; a point mutation that changes an adanine to a thiamine (changes the product from a glutamate to a valine residue)

34
Q

what happens when a valine is present on the beta-hemoglobin?

A

it is going to create a polymerization prone molecule

35
Q

populations with high incidence of HbS may have other variant hemoglobins such as what?

A

HbC and beta-thalassemia

36
Q

what exactly happens when you have that beta-globin S variant?

A

the variant hemoglobin polymerizes and forms a chain of hemoglobin polymers that extends and extends; the polymer chain is growing within the cell and is stretching it out

37
Q

what makes the polymerization of the variant hemoglobin in sickle cell anemia more likely?

A

hypoxia, intracellular dehydration, low pH (decreased O2 affinity) and sluggish blood flow

38
Q

due to the increased fragility of sickled cells, what can occur?

A

intravascular hemolysis

39
Q

what is the hallmark presentation of patients with sickle cell anemia?

A

vaso-occlusive effects (acute respiratory distress, acute chest syndrome, autosplenectomy and infections, aseptic bone necrosis and osteomyelitis)

40
Q

How is the diagnosis of SS disease made?

A

hemoglobin electrophoresis

41
Q

what hemoglobin is present for sickle cell anemia?

A

S hemoglobin

42
Q

what hemoglobin is present for SC disease and what are the characteristics?

A

C hemoglobin; milder than SS, Hgb C can crystalize but it does not polymerize

43
Q

what do the RBCs look like in SC disease?

A

you are more likely to see target cells rather than true sickle cells

44
Q

what are three ways you can treat sickle cell anemia?

A

hydroxyurea, supportive care, and CRISPR

45
Q

how do you make beta-globin?

A

you need one gene per chromosome–> so 2 genes total

46
Q

how do you make alpha-globulin?

A

2 genes per chromosome–> so 4 genes total

47
Q

what causes beta-thal triat/minor?

A

a mutation on one of the two beta-globin genes

48
Q

what causes beta-thal major?

A

with mutations on both of the beta-globin genes- so no beta-globin

49
Q

what is the effect of beta-thal major?

A

not only hemolytic anemia but also ineffective erythropoiesis as well (hypoproliferative)

50
Q

what two effects does ineffective erythropoiesis have?

A

causes anemia and there is a suppression of hepcidin

51
Q

what is the effect of suppression of hepcidin?

A

increased iron absorption by gut enterocytes–> systemic iron overload

52
Q

in beta thal major, what happens when the erythropoietin is increased but there is still ineffective erythropoiesis?

A

marrow expansion–> causes skeletal deformities

53
Q

what are the 3 final outcomes of beta-thal major?

A

severe anemia, preferential switch to Hgb F, and dramatic medullary and extramedullary hematopoiesis

54
Q

what is the clinical presentation of beta-thal minor?

A

microcytic anemia, mild and often asymptomatic

55
Q

why is it important to differentiate between beta-thal minor and iron-deficiency?

A

you can pass beta-thal minor down to your kids

56
Q

what do you get if 3 genes of alpha-globin are hit?

A

HbH disease

57
Q

what is HbH/ what are the characteristics of HbH?

A

it is a tetramer of beta-globin, it has a high affinity for O2- so it is a poor oxygenator

58
Q

what is the result of HbH disease?

A

anemia and splenomegaly

59
Q

what do you get if four alpha genes are hit in alpha-thalassemia?

A

Hb Bart’s disease (Hydrops fetalis)

60
Q

what happens when you don’t have any alpha-globin?

A

you are going to rely on very very immature hemoglobins in the embryonic fetal stagers, and the embryonic fetal hemoglobin is terrible at delivering oxygen

61
Q

what is the outcome of not having any alpha-globin genes?

A

anemia and tissue hypoxia, which leads to heart failure and extramedullary erythropoiesis

62
Q

the heart failure seen in hydrops fetalis leads to what?

A

edema, ascites, pleural effusion, large heart, and pericardial effusion

63
Q

what are the anchored membrane proteins that are missing in patients with paroxysmal nocturnal hemoglobinuria?

A

CD55 and CD59

64
Q

what is the result of not having CD55 and CD59?

A

you get complement settling on your RBCs and the MAC forms and the cell lysis

65
Q

what mutation typically causes paroxysmal nocturnal hemoglobinuria?

A

mutation on the PIGA gene

66
Q

what are the characteristics of PIGA mutations?

A

they are acquired (somatic), they affect a HSC- thus all derived cells are affected

67
Q

what is PNH a risk factor for?

A

MDS/AML

68
Q

How do you treat PNH?

A

turn off complement: eculizamab is a targeted therapy that blocks C5–> C5a

69
Q

what happens when you block complement?

A

prone to getting neisserial infections like meningitis

70
Q

how can immunohemolytic anemia be categorized?

A

autoimmune or drug induce and alloimmune

71
Q

what would you perform to detect the presence of antibody bound to the red cell surface?

A

Direct antiglobulin test (DAT) aka Coombs test

72
Q

what would you perform to detect antibodies in the plasma?

A

indirect antiglobin test (IAT) aka the indirect Coombs test

73
Q

When you have hemolytic anemias from this autoimmune or drug induced source, they are broadly classified into what?

A

warm and cold hemolytic anemias

74
Q

Which Ig subtype is most typically bound at warm temperatures?

A

IgG

75
Q

which Ig subtype is most typically bound at cold temperatures?

A

IgM

76
Q

where are cold hemolytic anemias more likely to manifest?

A

in the nose and fingertips

77
Q

What does a peripheral smear look like in a patient with auto immune hemolytic anemia (AIHA)?

A

microspherocytes and polychromasia

78
Q

What could cause hemolysis due to read cell trauma?

A

mechanical shear like from a prosthetic heart valve

SBL (14 decks)

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