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Anemia Flashcards

1
Q

Describe the basic shape of RBCs

A

Anucleate biconcave discs

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2
Q

Ratio of RBCs:WBCs in the peripheral blood

A

About 1000:1

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3
Q

What is the first stage of a RBC released from the marrow into peripheral blood? Describe its appearance

A

Reticulocyte

Cytoplasm may be blue-pink due to residual RNA (polychromasia)

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4
Q

What is the normal life span of a RBC?

A

120 days

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5
Q

What is the function of an RBC membrane skeleton?

A

Control biconcave shape and cell deformability

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6
Q

List some basic components of the RBC membrane

A

Phospholipid bilayer with glycolipids and cholesterol

Integral proteins span the bilayer

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7
Q

Describe the basic structure of heme

A

4 pyrrole groups joined into a large ring with a ferrous ion (Fe2+) in the center

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8
Q

Describe the basic structure of globin chains

A

~150 amino acids per chain

Heme binds to a specific region of each chain

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9
Q

Describe the basic structure of hemoglobin. What si the structure of the most common form of adult hemoglobin?

A

Two globin dimers and heme form hemoglobin

Hemoglobin A has 2 alpha and 2 beta globin chains

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10
Q

What organ removes aging RBCs from the circulation? How?

A

Spleen

Monouclear phagocytic engulfment

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11
Q

When hemoglobin is broken down, what are the elements it is broken into and how are they used?

A

Heme is divided into iron (gets recycled) and porphyrin rings (eliminated as bilirubin)

Globin is dismantled into amino acids

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12
Q

Accelerated RBC destruction is known as….

A

Hemolysis

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13
Q

Define anemia

A

Reduced O2 carrying capacity of the blood

Reduction below normal limits of total circulating RBC mass by either reducing volume of packed cells or reducing hemoglobin concentration

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14
Q

What are three general causes of anemia?

A

Blood loss
Hemolysis
Reduced RBC production

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15
Q

Some intrinsic abnormalities of RBCs that may lead to hemolysis are…

A

Membrane disorder
Enzyme deficiency
Hemoglobin synthesis disorder
Acquired disorder

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16
Q

Some extrinsic abnormalities of RBCs that may lead to hemolysis are…

A 
Antibody mediated
Mechanical trauma
Infections
Chemical injury
Sequestration
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17
Q

Microcytic anemia may be seen in what diseases?

A

Iron deficiency
Thalassemias
Anemia of chronic disease

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18
Q

Macrocytic Anemia may be seen in what diseases?

A

Vitamin B12 or Folate deficiency (megaloblastic anemia)

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19
Q

What is the MCV in microcytic anemia? Macrocytic? Normocytic?

A

Normocytic - 80 - 100 fL
Microcytic - below 80 fL
Macrocytic - above 100 fL

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20
Q

List some general pathological characteristics of hemolytic anemias

A

Shortened RBC life span
Accumulation of hemoglobin catabolism products
Compensatory increase in erythropoiesis in marrow

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21
Q

Describe what intravascular hemolysis is and what it may lead to

A

RBCs are destroyed within the vascular compartment

May cause hemoglobinemia, hemoglobinuria, and hemosiderinuria

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22
Q

What should you look for in blood samples of anemic patients to detect potential hemolysis?

A

Haptoglobin

If haptoglobin levels are low, you know there is some kind of hemolysis occuring. Free hemoglobin will form complexes with haptoglobin and be removed by the liver.

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23
Q

Describe what extravascular hemolysis is and what is might lead to

A

RBCs are destroyed primarily by tissue macrophages

May cause splenomegaly

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24
Q

Hereditary Spherocytosis

What is the basic pathological problem?

A

Hereditary (autosomal dominant mostly) problem with intrinsic defect in RBC membrane

Results in spheroid RBCs that are less deformable and more vulnerable to splenic sequestration and destruction

Lower membrane stability and loss of membrane fragments

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25
Q

Hereditary Spherocytosis

Autosomal dominant form is primarily a defect in…

A

Ankyrin gene

Less synthesis of ankyrin leads to less synthesis of spectrin

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26
Q

Hereditary Spherocytosis

Autosomal recessive form is primarily a defect in…

A

alpha-Spectrin gene

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27
Q

Hereditary Spherocytosis

What will improve their symptoms?

A

Spenectomy

Spherocytes will persist, but the anemia will improve

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28
Q

Hereditary Spherocytosis

What is seen on the peripheral blood smear?

A

Spheroidal RBCs that are abnormally small and do not have a central zone of pallor

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29
Q

Hereditary Spherocytosis

Clinical Symptoms/Features

A

Anemia
Splenomegaly
Jaundice

May be asymptomatic in 20-30% of people

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30
Q

Hereditary Spherocytosis

How is it diagnosed?

A

Family history
Hematologic findings
Increased mean cell hemoglobin conc.
Lab evidence of increased osmotic fragility

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31
Q

G-6-PD Deficiency

What is the inheritance?

A

X linked, so mostly males are affected

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32
Q

G-6-PD Deficiency

What is the normal function of G-6-PD?

A

Converts NADP to NADPH, allowing for the conversion of GSSG (oxidized glutathione) to GSH (reduced glutathione)

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33
Q

G-6-PD Deficiency

What are the symptoms?

A

Usually asymptomatic until they have some infection, oxidative stress, exposure to certain drugs or toxins

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34
Q

G-6-PD Deficiency

What is the characteristic finding on histology?

A

Heinz bodies

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35
Q

G-6-PD Deficiency

How are Heinz bodies formed?

A

Due to H2O2 accumulating and oxidizing sulfhydryl groups of globin chains. This denatures the hemoglobin and forms Heinz bodies, which attach to the RBC memrbane and cause damage and decreasing deformability

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36
Q

G-6-PD Deficiency

What is a characteristic finding on peripheral blood smear? How are they formed?

A

Bite cells
Formed as the RBCs+Heinz bodies pass through spleen. Macrophages bite the Heinz bodies and lead to loss of membrane and formation of spherocytes

37
Q

What are two problems with hemoglobin synthesis that may lead to hemolytic anemia?

A

Structually abnormal globin synthesis (sickle cell)

Deficient globin synthesis (thalassemia)

38
Q

Sickle Cell Disease

What is the mutation that causes this disorder?

A

Mutation in 6th position of the beta-globin gene (substitute Val->Glu)

39
Q

Sickle Cell Disease

What is the pathogenesis?

A

Hemoglobin S molecule is formed, which will aggregate and polymerize

RBC becomes distorted into the sickle shape

40
Q

Sickle Cell Disease

What are some factors that may induce sickling in these patients?

A

More HbS synthesis
MHC increase
Fall in pH

41
Q

Sickle Cell Disease

What are the two major clinical consequences of this disease?

A

Chronic hemolytic anemia

Occlusion of small blood vessels

42
Q

Sickle Cell Disease

How is the spleen involved in the pathogenesis?

A

Spleen may play a role in the hemolysis (rigid sickled RBCs may become sequestered there)

Over time, hypoxic tissue damage may occur and the spleen may become small and fibrotic (“auto-splenectomy”)

43
Q

Sickle Cell Disease

What is is the clinical outcome of occlusion of small blood vessels?

A

Widespread microvascular obstruction from rigid red cells may result in ischemic damage

Intermittent, sudden episodes are called vasoocclusive crises

44
Q

Sickle Cell Disease

How may this be diagnosed?

A

Ordinary peripheral blood smear can show sickled cells

Blood sample may be induced to show sickling

Usually diagnosed by hemoglobin electrophoresis

45
Q

Sickle Cell Disease

What group of people is this more commonly seen in?

A

African Americans

46
Q

Thalassemia

What is the general pathological problem?

A

Genetic disorder characterized by decreased synthesis of either alpha or beta chains of hemoglobin A.

The consequences derive from diminished synthesis of one globin chain leading to low intracellular hemoglobin or excess of the other kind of chain

47
Q

Alpha Thalassemia

Where are the alpha globin chain genes?

A

There are two alpha genes on chromosome 16.

48
Q

Alpha Thalassemia

4 degrees of this disease may result. List them

A

Silent carrier -a/aa

Alpha thalassemia trait –/aa or -a/-a

HbH disease –/-a

Hydrops fetalis –/–

49
Q

Beta Thalassemia

What causes the anemia?

A

Reduced synthesis of beta-globin, leading to inadequate Hgb A formation

Hemolysis is caused by excess alpha chains, which form insoluble aggregates

50
Q

What is the major difference between Thalassemia major and Thalassemia minor?

A

Major - severe disease with reliance on transfusions

Minor - asymptomatic, mild, or absent anemia and some RBC abnormalities

51
Q

Beta Thalassemia Major

What are some clinical observations?

A

Marrow space expanding into skull (hair on end appearance of the Xray)

Hepatosplenomegaly

Multiple transfusions necessary

52
Q

Beta Thalassemia Minor

What are the clinical associations?

A

Minor microcytic hypochromic anemia

“Target” cell - central pallor with a dot in the middle
RBCs have “bell” shape

53
Q

What is the only acquired defect in the RBC membrane?

A

PNH

Paraoxysmal Nocturnal Hemoglobinuria

54
Q

PNH

What is the pathogenesis?

A

Stem cell disorder that results from a mutation in the PIGA gene

Leads to a deficiency of GPI anchor and lack of expression of GPI-linked proteins

55
Q

List some important GPI-linked proteins.

A

CD55
CD59
C8 binding protein

56
Q

PNH

Clinical Findings

A

Classic intravascular hemolysis
Infections and venous thrombosis

May occassionally evolve to aplastic anemia or leukemia

57
Q

What are two causes of mechanical RBC hemolysis?

A

Prosthetic cardiac valves

Narrowing of small vessels and fibrin deposition (Microangiopathic hemolytic anemia)

58
Q

List some forms of Microangiopathic hemolytic anemia

A

TTP
HUS
DIC

59
Q

How can you confirm Microangiopathic hemolytic anemia with a blood smear?

A

See schistocytes

60
Q

In anemias from impaired RBC production, what are some general problems that can halt RBC production?

A

Deficient heme synthesis
Deficient DNA synthesis
Multiple mechanisms

Disordered proliferation and maturation of the stem cells

61
Q

What is the most common cause of iron deficient anemia?

A

Chronic blood loss, usually in the GI tract

62
Q

Describe the pathogenesis of iron deficient anemia (what happens first, etc)

A

Stored iron (ferritin) is depleted first, the circulating iron goes low

Hemoglobin eventually goes low and the RBCs become microcytic with reduced hemoglobin concentration

63
Q

Symptoms of iron deficient anemia

A

Nails develop ridges, get spoon shape
Tongue may become smooth
Intestinal malabsorption
Esophageal webs (rare)

64
Q

What would the blood smear of iron deficient anemia look like?

A

RBCs have a larger central pallor than usual

65
Q

What is the general problem in megaloblastic anemia?

A

Deficient DNA synthesis from a Vit B12 or Folate deficiency

66
Q

Megaloblastic Anemia

What is seen in the proliferating cells?

A

Enlarged RBC precursors (megaloblasts)

Enlarged red cells (macrocytes)

67
Q

Megaloblastic Anemia

How does impaired DNA synthesis cause enlargement?

A

Abnormal cell maturation and division

68
Q

What could potentially cause a B12 deficiency?

A 
Intrinsic Factor (IF) deficiency
Pancreatitis
Gastrectomy
Ileal resection
Parasites (Fish tapeworm)
69
Q

What is pernicious anemia?

A

Vit B12 deficiency secondary to gastritis with underproduction of IF

70
Q

What is the role of IF in B12 absorption?

A

Intrinsic Factor (IF) from the stomach needs to bind B12 for its absorption in the distal ileum

71
Q

Why is Vitamin B12 necessary for humans?

A

Necessary cofactor in methionine synthesis (deficiency of B12 leads to less THF for the reaction)

Isomerization of methylmalonyl CoA to succinyl CoA

72
Q

What may be seen on peripheral blood smear in B12 deficiency?

A

Megaloblastic anemia

Leukopenia with hypersegmented granulocytes

73
Q

Describe the problems Megaloblastic Anemia may cause in the CNS

A

Subacute combined degeneration

-affects sensory and motor tracts

74
Q

What are some symptoms of Megaloblastic Anemia from folate deficiency?

A

Megaloblastic anemia is identical to B12 deficiency, but there are no CNS symptoms in folate deficiency.

75
Q

Anemia of Chronic Disease
You may see high plasma levels of….
What does this compound do?

A

Hepcidin

High levels of hepcidin may block transfer of iron from macrophages to RBC precursors

76
Q

List the pathological consequences of Anemia of Chronic Disease

A

Microcytic anemia with low serum iron
High ferritin
Decreased total iron binding capacity
Increased bone marrow iron stores

77
Q

Aplastic Anemia

What will you find in the peripheral blood?

A

“Pancytopenia”
Anemia
Granulocytopenia
Thrombocytopenia

78
Q

Aplastic Anemia

What is the pathologic problem?

A

Failure or suppression of stem cells leading to a hypocellular marrow

May be caused by defect in HSCs, bone marrow stroma, or suppression by T cell mediated immunity

79
Q

Aplastic Anemia

What would you see in the bone marrow?

A

Hypocellular bone marrow

Increased fat

80
Q

Aplastic Anemia

How should you treat?

A

Could use HSC transplant, but this is difficult and the morbidity/mortality is high

81
Q

What is the MCH? How is it calculated?

A

Mean Corpuscular Hemoglobin

MCH = (Hemoglobin x 10)/RBC

82
Q

What is the MCHC? How is it calculated?

A

Mean corpuscular hemoglobin concentration

Hemoglobin/Hematocrit = MCHC

83
Q

In hypochromic anemias, how are the MHC and MCHC affected?

A

Both are decreased in hypochromic anemias (like iron deficiency or thalassemia)

84
Q

Give an example of a hyperchromic anemia.

How are the MCH and MCHC affected?

A

Hereditary spherocytosis

MCHC will be increased

85
Q

In macrocytic anemias, how is the MCHC affected?

A

It is normal.

MCH is high (hemoglobin is increased), but the cells themselves are also large.

86
Q

What is RDW a measure of?

A

Red Cell Distribution

Measure of the variability in RBC size

87
Q

What is anisocytosis?

A

Variation in RBC size, measured by RDW

88
Q

What is poikocytosis?

A

Variation in RBC shape

MHD (57 decks)

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