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SP16- Gen Path Exam 2 > Red Blood Cell Disorders > Flashcards

Red Blood Cell Disorders Flashcards

1
Q

Define anemia.

A

A reduction in red cell mass with consequent decrease in oxygen transport capacity of blood

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2
Q

What are the three clinical parameters used in testing for anemia?

A
  1. Red cell count
  2. hemoglobin concentration
  3. hematocrit

*all reflect but do not directly measure red cell mass

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3
Q

What is the result of impaired tissue oxygenation that is associated with anemia?

A
  • shortness of breath
  • weakness
  • fatigue
  • pallor
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4
Q

What are the three common mechanisms for establishing anemia?

A
  1. RBC loss (hemorrhage, trauma, GI disease)
  2. Decreased survival of RBC (malaria, transfusions, etc)
  3. Decreased production of RBC (nutrition deficiency, aplastic anemia, myelophthistic processes)
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5
Q

What is “aplastic anemia?”

A

a condition that occurs when the body stops producing enough new RBCs

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6
Q

What is polycythemia?

A

an increase in red cell mass (opposite of anemia)

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7
Q

What are the laboratory tests for anemia?

A
  1. Complete Blood Count (CBC)
  2. Blood smear review
  3. Reticulocyte Count (new/immature RBC)
  4. Iron Indices (transferrin, ferritin, B12, folate)
  5. Hemolysis Work-up (bilirubin, haptoglobin, LDH, Coomb’s test, Plasma hemoglobin, electrophoresis)
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8
Q

What is the Coomb’s Test?

A

It detects antibodies against RBCs that are present unbound in the patient’s serum. In this case, serum is extracted from the blood sample taken from the patient.

(“Coomb” rhymes with “womb” = common in prenatal testing)

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9
Q

Hemorrhage can be either _____ or ______.

A

acute

chronic

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10
Q

How much blood loss can a young, healthy individual handle with few symptoms?

A

500-1000 mL

15-20% total blood volume

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11
Q

Some healthy individuals could experience a ______ response (sweating, weakness, nausea, slowed HR, and hypotension) with a loss of 1000mL. What level of rapid blood loss will produce shock?

A

vasovagal

2000 mL

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12
Q

With controlled blood loss, how long does it take for interstitial fluid to redistribute into the vascular space? Why does it do this?

A

24 hours

-its an attempt to re-expand the vascular volume

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13
Q

RBC production is mediated by _______. RBC production will cause an increase in the ______ count in the peripheral blood.

A

erythropoietin

reticulocyte

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14
Q

What is chronic hemorrhage?

A

the rate of RBC loss exceeds the capacity for RBC regeneration (could be due to decreased iron that is available)

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15
Q

What are two common causes of iron deficiency?

A
  1. Chronic bleeding of GI tract due to ulcer or neoplasm

2. Menorrhagia (heavy menstrual bleeding)

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16
Q

______ anemias are due to decreased red blood cell survival.

A

Hemolytic

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17
Q

Hemolytic Anemia can be either _____ or ______.

A 
intravascular
extravascular (more common)
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18
Q

What is the difference between intravascular and extravascular hemolytic anemia?

A

intravascular: destruction of red cells within the circulation
extravascular: destruction of red cells within the reticuloendothelial system (tissue macrophages of the spleen and liver)

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19
Q

Intravascular hemolysis can be immune, such as in _________, or it can be non-immune, such as in _______.

A 
Immune = transfusion reactions
Non-immune = mechanical trauma such as shearing by defective heart valve
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20
Q

What is the key feature of intravascular hemolysis?

A

decrease in serum haptoglobin

this causes a problem because hemoglobin&raquo_space;haptoglobin….so now hemoglobin is excreted in the urine = hemoglobinuria

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21
Q

True or False: Jaundice is associated with intravascular hemolysis.

A

True

hemoglobin»haptoglobin = hemoglobinuria
hemoglobin = toxic to kidney
iron accumulates in proximal tubules = hemosiderinuria
heme conversion to bilirubin = jaundice
degree of jaundice depends on fxnl capacity of the liver

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22
Q

True or False: Both intra- and extra-vascular hemolysis have immune and non-immune causes.

A

True

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23
Q

Immune-related extravascular hemolysis is caused by ____ defects.

A

extrinsic

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24
Q

Non-immune related extravascular hemolysis is caused by _____ defects.

A

intrinsic

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25
Q

Give three examples of extrinsic (immune) defects.

A
  1. autoimmune
  2. erythroblastosis fetalis
  3. transfusion reaction
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26
Q

Give three examples of intrinsic (non-immune) defects.

A
  1. RBC membrane defects
  2. hemoglobinopathies
  3. metabolic defects
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27
Q

_______ is also associated with extravascular hemolysis (destruction in the spleen or liver) because free hemoglobin is not released directly into the blood/urine and breakdown products are therefore increased.

A

jaundice

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28
Q

True or False: Hepatosplenomegaly is associated with intravascular hemolysis.

A

false, EXTRAvascular…spleen and liver breakdown the RBC

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29
Q

With extravascular hemolysis, which defect type is inherited?

A

intrinsic are inherited (non-immune defects)

  • hemoglobin abnormality
  • membrane abnormality
  • lack of globin chains
  • metabolic defect
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30
Q

Classify “hereditary spherocytosis” based on type of hemolytic anemia and defect.

A 
EXTRAvascular hemolysis (spleen or liver)
INTRINSIC defect
MEMBRANE defect
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31
Q

What is hereditary spherocytosis?

A

an inherited defect in the red cell membrane that results in less deformability of the cell = can’t squeeze through splenic sinusoids = sequestered and destroyed

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32
Q

What do spherocytes look like?

A

Round balls, not biconcave disks

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33
Q

Hereditary spherocytosis is either a qualitative or quantitative deficiency of which structural protein of the cytoskeleton?

A

spectrin

Spectrin + Spheres = MINE
M embrane defect
IN trinsic defect
E xtravascular hemolysis

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34
Q

How serious is Hereditary spherocytosis? Is it curable?

A

its an autosomal dominance inheritance pattern that manifests in adult life with VARIABLE severity

  • removal of the spleen results in normal RBC survival but not normal red cell morphology
  • following splenectomy, spherocytes ARE still produced but destruction of cells is decreased
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35
Q

Sickle Cell anemia is a type of ________ hemolysis associated with ________ defects of the _______.

A

extravascular
intrinsic
hemoglobin

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36
Q

Sickle cell anemia is autosomal _____ condition that causes a _______ substitution in DNA between valine and glutamic acid at position 6 in the beta chain.

A

codominant (occurs in homozygotes for HbS)

single base pair

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37
Q

What happens to the hemoglobin in sickle cell anemia?

A

the globin chain is defective and causes the hemoglobin to gel upon deoxygenation and assume its sickle shape

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38
Q

Why are the sickled cells a problem?

A
  • they are rigid and vulnerable to splenic sequestration

- they can block the microcirculation causing ischemia and/or infarction

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39
Q

What are the two leading causes of ischemia-related death for patients affected by Sickle Cell Anemia?

A
  1. Acute chest syndrome

2. Stroke

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40
Q

True or False: Heterozygotes of sickle cell are clinically asymptomatic because less than half of the hemoglobin is abnormal and HbS concentration is too low to cause sickle shaped cells.

A

True,

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41
Q

___% of blacks in the USA are heterozygous carriers of sickle cell trait.

A

8

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42
Q

True or False: Autosplenectomy is a complication of hereditary spherocytosis.

A

False, autosplenectomy = sickle cell anemia

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43
Q

What is Thalassemia?

A

INTRINSIC defect of EXTRAVASCULAR hemolysis

-results in diminished or absent synthesis of either the alpha or beta globin chains of hemoglobin

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44
Q

The type of thalassemia is named for the ____.

A

globin chain that is produced in a reduced amount

45
Q

What is the principal clinical manifestation of thalassemia?

A

anemia (due to decreased hemoglobin production)

thalassemia leads to anemia…thalassemia leads to anemia…thalassemia leads to anemia….thalassemia leads to anemia….thalas…..you get it

46
Q

True or False: Thalassemia is common in persons of Mediterranean, African, and Southeast Asian descent.

A

True

47
Q

True or False: Thalassemia reduces the impact of malaria.

A

True

(both sickle cell and thalassemia change the hemoglobin chains…and they both provide protection against malaria. coincidence?)

48
Q

In almost all cases of Thalassemia there is a moderate to marked ________ with target cells and ________ of the RBCs on the blood smear.

A 
microcytosis (low MCV= small cells)
basophilic stippling (small dots in the periphery from ribosomes)
49
Q

What type of deficiency causes a metabolic defect (intrinsic) that results in extravascular hemolytic anemia?

A

Glucose-6 Phosphate Dehydrogenase (G6PD) deficiency

  • sex linked defect (primarily black men)
  • red cells are susceptible to oxidant injury usually precipitated by drugs/toxins or infections
  • RBC membrane is less flexible and subjected to extravascular hemolysis in the spleen
50
Q

What is the cytomorphologic hallmark of G6PD deficiency?

A

“bite” cells

-not very flexible

51
Q

True or False: In the absence of the oxidant trigger (antimalarials, sulfonamides, etc), G6PC deficiency is asymptomatic.

A

True

52
Q

True or False: Bite Cells are more flexible than normal RBCs.

A

False

53
Q

Extrinsic defects associated with extravascular hemolysis. include _______ disease of the newborn and _____ hemolysis.

A

hemolytic

autoimmune

54
Q

Hemolytic disease of the newborn occurs _______.

A

in utero

55
Q

What is another name for hemolytic disease of the newborn (HDN)? What causes it?

A

erythroblastosis fetalis

  • blood group incompatibility between mother and fetus
  • fetal RBC expresses antigens inherited from the father that are not present in the mother
  • during the third trimester or during delivery, the mother is exposed to the antigens = antibody response
  • during future pregnancy, the mother’s immune system makes antibodies that cross the placenta and attach to fetal RBC = extravascular hemolysis of RBC in new fetus (liver and spleen)
56
Q

Which antigens are most important in the Hemolytic Disease of the Newborn?

A

ABO

Rh (anti-D)

57
Q

Rh-negative mothers are given _____ within 72 hours of delivery of an Rh-positive fetus. Why?

A

anti-D (Rhogam)
-anti-D binds to the Rh-positive fetal cells and removes them from maternal circulation before the mother can generate an antibody response and become sensitized

58
Q

When does ABO hemolytic disease occur?

A

Group A or Group B infants born to group O mothers
-certain group O mothers produce IgG anti-A or anti-B in addition to the usually IgM antibodies (lysis of fetal RBC is minimal because fetal cells express A or B antigens weakly)

59
Q

True or False: IgM does not cross the placenta.

A

True

60
Q

True or False: IgG can cross the placenta.

A

True

IgM = M om only
IgG = G oes across
61
Q

What is a hemolytic transfusion reaction?

A

a type of intravascular hemolysis
-transfusion of incompatible red cells into a sensitized patient results in binding of antibody (in patient) to antigen (transfused RBC) with activation of complement (lyses antibody-coated RBC) and immediate intravascular hemolysis

62
Q

Which antigen type is most important in hemolytic transfusion reactions?

A

ABO

63
Q

Hemolytic transfusion reactions will activate the coagulation cascade with bleeding, _____ failure, ______ and ______.

A

renal
shock
death

64
Q

True or False: Hemolytic Transfusion Reactions are always intravascular.

A

False,
following transfusion = intravascular
delayed reaction = extravascular

65
Q

What is autoimmune hemolysis?

A
  • extravascular or intravascular hemolysis reaction
  • patient makes antibodies to his/her own RBCs
  • antibody coated cells can be removed by the reticuloendothelial system = extravascular
  • antibody coated cells can be lysed via complement activation = intravascular
66
Q

What is the hallmark of autoimmune hemolytic anemia?

A

spherocytes

67
Q

What are spherocytes?

A
  • -partial loss of red cell membrane (cytoskeleton) makes the RBC ball-like and less deformable
  • they are sequestered by the spleen and therefore further enhance the anemia
68
Q

What test is done to determine presence of autoimmune hemolytic anemia?

A

The Coomb’s Test

-agglutinaton test/RBC aggregation

69
Q

Name two examples of extrinsic defects contributing to hemolytic anemia that are the result of mechanical trauma. Are these intra- or extra-vascular hemolysis?

A
  1. Cardiac Valve Prosthesis
  2. DIC

INTRAVASCULAR occuring within the circulation (not the reticuloendothelial/spleen/liver)

70
Q

How do cardiac valve prostheses contribute to intravascular hemolytic anemia?

A

-RBCs are disrupted by physical trauma as they pass through areas of turbulence and abnormal pressure related to abnormal valve function

71
Q

How does DIC contribute to intravascular hemolytic anemia?

A

-RBCs are lysed as they pass through fibrin clots/strands in the microcirculation

72
Q

What is a good indication of hemolysis due to mechanical trauma?

A

Schistocytes

-RBC fragments that lost a large portion of their membranes and look mishapen and squashed

73
Q

True or False: Infections can cause intravascular hemolytic anemia.

A

True!

  • parasites can infect RBCs and cause lysis of RBC during maturation (ex. Malaria)
  • different degrees experienced by different patients
74
Q

How do nutrition deficiencies lead to anemia?

A

deficiency of a substance needed for erythropoiesis will decrease the red cell PRODUCTION

75
Q

What are the common nutrition deficiencies associated with anemia?

A

iron
folate
B12

76
Q

_____ deficiency is the most common cause of anemia worldwide. It is needed for _______, _______, and a variety of enzymes.

A

Iron
hemoglobin
myoglobin

77
Q

What are the common settings for iron deficiency anemia?

A
  1. inadequate intake (infants, alcoholics, elderly)
  2. increased demands (pregnancy, adolescents)
  3. increased loss (bleeding, cancer)
78
Q

What happens to red cells when there is inadequate iron intake?

A

they become smaller (MICROCYTIC) and contain less hemoglobin (HYPOCHROMIC) than usual

79
Q

Anemia develops _____ and low levels of Hb can be tolerated with _____ symptoms.

A

insidiously (gradually)

minimal

80
Q

Describe the laboratory results used to study iron deficiency anemia.

A
  • low serum iron
  • low serum ferritin
  • increased serum iron-binding capacity
  • microcytic red cells
  • hypochromic red cells
81
Q

True or False: Iron deficiency anemia may be linked to a more serious condition.

A

True, chronic blood loss associated with cancer is a possibility

82
Q

Both B12 and folate are involved (either directly or as cofactors) in the synthesis of _______, one of the _____ bases in DNA.

A

thymidine

purine

83
Q

________ anemia results from folate and B12 deficiency.

A

Megaloblastic

84
Q

Why is it called “megaloblastic” anemia?

A

B12 + folate = thymidine = DNA base

  • impaired DNA synthesis = delayed mitotic division
  • nucleus does not mature appropriately but RNA synthesis and cytoplasmic maturation proceed normally
  • results = abnormally large red cell precursors (megalobasts), decreased production of mature RBC, and abnormally large red cells (macrocytes)
85
Q

What is the histological evidence of megaloblastic anemia?

A
  • abnormally large red and white cell precursors
  • increased MCV
  • hypersegmented neutrophils (lobulated)
86
Q

Megaloblasts accumulate in the _____ and release too few RBCs into the peripheral blood, causing anemia.

A

bone marrow

87
Q

Megaloblasts may undergo ______ in the marrow or may be destroyed by ______ cells in the marrow.

A

autohemolysis
phagocytic
(ineffective erythropoiesis)

88
Q

True or False: The impairment of DNA synthesis associated with megaloblastic anemia is systemic and affects other rapidly dividing cells in the body.

A

True.

89
Q

In what food source is folate found? Is it stored in the body?

A

in fresh vegetables (absorbed through proximal small intestine)
body stores are SMALL

90
Q

In what food source is B12 found? Is it stored in the body?

A

in animal foods (absorbed in distal ileum; IF-b12 complex attaches to epithelial cells)
*body stores are LARGE

91
Q

Absorption of B12 requires _____, a protein produced by parietal cells of the gastric mucosa.

A

intrinsic factor

92
Q

Patients with _____ anemia have autoantibodies directed at intrinsic factor.

A

pernicious

B12 deficient and association with atrophic gastritis

93
Q

Which transport protein is responsible for delivering the absorbed B12 to the liver and other cells?

A

transcobalamins

–glycoprotein produced by the salivary glands, protects b12 from acid degradation–

94
Q

True or False: Folate deficiency can be associated with neurologic symptoms.

A

False, B12 can!!

95
Q

Name two examples of anemia associated with decreased red cell production.

A
  1. aplastic anemia

2. myelophthisic anemia

96
Q

What is aplastic anemia?

A

a stem cell abnormality results in marked diminution of hematopoiesis
-production of all cellular elements of the blood are decreased

97
Q

True or False: Over half of the cases of aplastic anemia have no known predisposing cause.

A

True, but viruses, drugs, and toxins have been implicated

98
Q

What type of treatment for aplastic anemia has been successful, especially in patients under 40 years old?

A

bone marrow transplantation

99
Q

What is myelophthisic anemia?

A

decreased production of red cells due to replacement (by tumor or fibrosis) of marrow elements

100
Q

What is often seen on a blood smear in a patient with myelophthistic anemia?

A

mishapen RBCs resembling teardrops

101
Q

What type of cancer is usually involved with myelophthistic anemia?

A

multiple myeloma

metastatic cancer

102
Q

What is polycythemia?

A

an increase in red cell mass (opposite of anemia)

“polyCYthemia”…“CYke! its not anemia”

103
Q

______ polycythemia occurs with hemoconcentration of red cells due to dehydration, vomiting, diarrhear, or excessive use of diuretics.

A

Relative

104
Q

______ polycythemia can be a primary or secondary phenomenon.

A

Absolute

105
Q

When does primary absolute polycythemia occur?

A

(polycythemia vera) non-regulated proliferation of red cells and myeloid cells

  • this is a stem cell disorder and is associated with normal or low levels of EPO
  • causes sludging of red cells in capillaries = neurologic and visual abnormalities
106
Q

How doe you treat polycythemia vera?

A

removal of excess RBC by phlebotomy

107
Q

How does secondary absolute polycythemia occur?

A

through stimuli that increase EPO

ex.: cyanotic heart disease, pulmonary disease, high altitude living, abnormal Hb, tumor producing EPO

108
Q

_______ levels are helpful in distinguishing primary from secondary absolute polycythemia.

A

erythropoietin
primary = normal or suppressed levels
secondary = increased levels

SP16- Gen Path Exam 2 (7 decks)

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