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Blood & Lymph > Anemia: Blood Loss/Hemolytic Anemia > Flashcards

Anemia: Blood Loss/Hemolytic Anemia Flashcards

1
Q

Severely anemic patients may develop fatty changes in their ______ (3) due to hypoxia.

A

liver, kidney or myocardium

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2
Q

2 types of hemolytic anemia

A
  1. intravascular
  2. extravascular
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3
Q

acute blood loss is mainly due to the loss of _____ and can lead to CV collapse → shock → death.

A

intravascular volume

(presentation depends on rate of hemorrhage & whether bleeding is internal or external)

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4
Q

Hemodilution

A

during acute blood loss → volume is restored by intravascular shift (water from interstitial fluid → vasculature → dilutes blood)

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5
Q

Hemodilution and a lowering of the hematocrit. The reduction in oxygenation due to acute blood loss triggers → EPO → stimulates erythroid progenitors (CFU-E) in the marrow.

A

EPO

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6
Q

Iron is recaptured during acute blood loss if RBCs ______ versus bleeding ______ which → iron loss.

A
  • extravasate from vessels into tissues
  • into the gut or out of the body
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7
Q

Early recovery from acute blood loss is often accompanied by _____.

A

thrombocytosis

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8
Q

Increased renal secretion of EPO → increased erythrocyte progenitors. What is their appearance early on? Later?

A
  • Early: normocytic, normochromic RBC
  • Later: ⇡ marrow production → reticulocytosis → macrocytic w/ polychromatophilic cytoplasm
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9
Q

Chronic blood loss only leads to anemia if the ______ or when iron reserves are depleted.

A

rate of loss exceeds the regenerative capacity of marrow

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10
Q

Age-dependent changes of RBC surface proteins triggers MF to destroy them in the ________ (3).

A

liver, spleen and bone marrow

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11
Q

Elevated EPO → elevated _____.

A

erythropoiesis

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12
Q

In all hemolytic anemias there is an increase in _____ (3).

A
  1. erythroid precursors
  2. hemosiderin
  3. reticulocytosis
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13
Q

Severe hemolytic anemia → extramedullary _____.

A

hematopoiesis (liver & spleen)

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14
Q

uncomplicated, chronic anemia → elevated ______.

A

unconjugated bilirubin (liver excretes bilirubin into GI = gallstones)

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15
Q

Most hemolytic anemias are _______ (intravascular/extravascular).

A

extravascular

(premature RBCs phagocytosis in spleen → splenomegaly)

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16
Q

In extravascular hemolytic anemia the RBC membranes are less deformable making them more likely to be sequestered by spleen → get stuck in ______ → MF destroy them in _____.

A
  • sinusoids
  • splenic cords
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17
Q

Intravascular hemolysis: causes (4)

A
  1. mechanical injury
  2. complement fixations
  3. intracellular parasites (malaria)
  4. toxins
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18
Q

Which toxic factor → intravascular hemolysis?

A

clostridial species (have enzymes that destroy RBCs)

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19
Q

What 2 findings are present in both intra- and extra-vascular hemolysis?

A
  1. jaundice
  2. anemia
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20
Q

Findings of extravascular hemolysis will demonstrate _______; while intravascular hemolysis will have _______ (3).

A
  • increased plasma haptoglobin
  • hemoglobinemia, hemoglobinuria, hemosiderinuria

(both present w/jaundice & anemia)

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21
Q

Why is there an increase in plasma haptoglobin in extravascular hemolysis?

A

hemoglobin escaping phagocytosis → binding to a2-globulin

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22
Q

Decreased haptoglobin in intravascular hemolysis → ______ (unique diagnostic feature/finding)

A

methemoglobin (red-brown urine)

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23
Q

Why do patients with intravascular hemolysis have renal hemosiderosis?

A

released iron accumulates inside the tubule cells

(iron is stored as hemosiderin in renal cells)

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24
Q
A

Hereditary spherocytosis

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25
Q

Parvovirus can cause aplastic crisis in which two inherited forms of hemolytic anemia?

A
  1. HS
  2. Sickle cell

(destroys RBC progenitors → compensatory erythropoiesis is outpaced → aplastic crisis)

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26
Q

What is a hemolytic crisis in patients with hereditary spherocytosis?

A

increased splenic RBC destruction

(ex: infectious mono)

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27
Q

Hereditary spherocytosis is due to which 2 _________ mutations.

A
  1. spectrin
  2. ankyrin

(mutations → destabilizes lipid bilayer)

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28
Q

spectrin

A

main membrane skeletal protein (alpha & beta chains) of RBC

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29
Q

ankyrin

A

binds spectrin to band 4.2 and band 3 (“tethering”)

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30
Q

Young HS RBCs are described as ______

A

normal shape

(they shed fragments as they age)

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31
Q

As the HS RBC ages and becomes less deformable →______ → MF destroy them.

A

splenic trapping & prolonged splenic exposure → erythrostasis

32
Q

HS inheritance

A

75% AD

(heterozygotes are born jaundiced and require transfusions)

33
Q

HS is diagnosed by _______ (2).

A
  1. osmotic lysis: more sensitive when incubated in hypotonic salt solution
  2. increased MCHC due to loss of K+/H2O → dehydration → increased [Hgb]
34
Q

HS is treated by splenectomy. _____ is fixed but _____ remains. Also increases the risk of _____.

A
  • anemia
  • spherocytosis
  • infection
35
Q

HS clinical features include: anemia, splenomegaly, ______ (2).

A
  1. jaundice
  2. gallstones
36
Q

G6PD causes _________ (intravascular/extravascular) hemolysis.

A

both

37
Q

Function of G6PD

A
  1. reduce NAPD → NAPDH
  2. oxidize glucose-6-phosphate
38
Q

Inherited variants of G6PD lead to misfolded proteins → making the enzyme more susceptible to ______.

A

proteolytic degradation

39
Q

What are 2 morphologic characteristics of G6PD Deficiency?

A
  1. Bite cells (aka degmacytes)
  2. Heinz bodies

(“blister cells” may also be seen: Hb collects on one side of the cell leaving the other clear)

40
Q

Howell-Jolly bodies are seen in both ______ & _____.

A
  • HS
  • Sickle cell
41
Q

Heinz bodies are membrane-bound precipitants formed by ______.

A

denatured globin

(caused by increased oxidants → dark inclusions - crystal violet stain)

42
Q

Heinz bodies can lead to a loss of ______ & intravascular hemolysis.

A

deformability

43
Q

Why are spherocytes seen in G6PD Deficiency?

A

MF “pluck out” or “take a bite” out of RBCs to remove the Heinz bodies. This leads to bite cells (aka degmacytes) or spherocytes if they are less severely damaged by this.

44
Q

Distinct features of G6PD deficiency

A

episodic hemolysis caused by oxidative stress: toxin, fava beans, infection

45
Q

Drugs that may trigger episodic hemolysis in patients w/G6PD deficiency (2)

A
  1. antimalarials: primaquine, chloroquine
  2. sulfonamides
46
Q

______ is seen during the recovery phase of hemolytic episodes in patients w/ G6PD deficiency.

A

reticulocytosis

47
Q

Which variant of G6PD deficiency has more severe bouts of intravascular hemolysis due to oxidative stress? Why?

A

Mediterranean variant

markedly reduced half-life of G6PD → marked intravascular hemolysis with oxidative stress

(African variant has a mildly reduced half life)

48
Q

Patients w/G6PD deficiency will have hemolytic episodes 2-3 days after exposure to oxidants → acute intravascular hemolysis. What are the key findings?

A

hemoglobinuria

(no signs of chronic hemolysis i.e. splenomegaly or cholelithiasis)

49
Q

Sickle cell disease is a common hereditary hemoglobinopathy that is caused by a point mutation in _____ , which leads to _______.

A
  • beta-globin
  • polymerization of deoxygenated Hgb
50
Q

Inheritance of Sickle cell disease is _______ .______ have sickle cell trait.

A
  • Autosomal recessive
  • heterozygotes for HbS (“AS”, nl: “AA”)
51
Q

_______% of African-Americans = heterozygous for HbS. Trait protective against ______.

A
  • 8-10
  • falciparum malaria
52
Q

In Sickle Cell Disease, polymerized deoxy-Hgb causes RBC distortion (“sickle cell”), which causes _______ and _______.

A
  • hemolytic anemia
  • microvascular obstruction → ischemic tissue damage.
53
Q

Normal adult RBCs = mainly _______ (type of hemoglobin). In Sickle cell, there is a point mutation in beta-globin which replaces ______ → _____ residue. *Different mutation (lysine residue) causes HbC variant;

A
  • HbA (α2β2)
  • glutamate → valine (HbS)

(HbC is glutamate → lysine; can be compound HbS/HbC (HbSC disease)

54
Q

How is the RBC membrane shape distorted in Sickle Cell Disease?

A

HbS molecules “stack” into polymers when deoxygenated → membrane defects = distorted shape.

55
Q

Low O2 and decreased intracellular pH promote sickling. Why?

A

Low pH → reduced O2 affinity → more deoxygenated Hb

56
Q

Interaction of HbS with other types of Hgb (i.e. heterozygotes) can be either inhibit or enhance HbS polymerization. Which inhibit and which enhance?

A
  • Inhibit polymerization: HbF & HbA
  • Enhance: HbC (causes dehydration of cell → increasing [HbS])

(concomitant alpha-thalassemia also inhibits polymerization)

57
Q

Decreased RBC transit through the ______ (3) increases the risk of occlusion in sickle cell disease.

A
  1. spleen
  2. bone marrow
  3. inflamed tissues
58
Q

2 mechanisms of damage in sickle cell disease?

A
  1. RBC dehydration
  2. microvascular occlusion
59
Q

How does RBC dehydration → hemolysis in sickle cell diseaes?

A

HbS stabs through membrane → influx of Ca2+→ activation of K+/H2O efflux

60
Q

How does RBC dehydration cause extravascular hemolysis triggered in sickle cell disease? Intravascular?

A
  1. Extravascular: repeated RBC dehydration → sickled cells destroyed by MF
  2. intravascular: mechanically fragle
61
Q

Describe the microvascular occlusions that occur in sickle cell disease

A

vasoconstriction or inflammation slows RBC movement in vascular beds → extended exposure to low O2 increases sickling → occlusion → ischemia → hypoxia/sickle cycle

(free Hgb from lysed cells also binds/inactivates NO which normally inhibits platelet aggregation)

62
Q

How is sickle cell anemia diagnosed?

A

metabisulfite (O2-consuming agent) + blood sample → induces sickling

(positive for trait and disease)

63
Q
A
64
Q

2 prominent phenotypes of patients with sickle cell disease

A
  1. “crewcut skull” on XR
  2. Chipmunk facies (prominent cheekbones)
65
Q

Target cells (from RBC dehydration) and Howell-Jolly bodies indicate which hemolytic disease?

A

sickle cell

66
Q

Howell-Jolly bodies are small nuclear remnants due to asplenia (enlarged spleen early in disease; red pulp congestion) eventually leads to ______

A

splenic infarct & fibrosis → autosplenectomy

67
Q

Describe the vaso-occlusive/pain crisis of sickle cell disease.

A

hypoxic injury/infarct → severe pain in bones, lungs, liver, brain, spleen, penis

68
Q

what is the most common cause of death in adult sickle cell patients? children?

A
  • adults: vaso-occlusive/pain crisis
  • children: infection H. flu
69
Q

What are 3 common syndromes caused by vaso-occlusive/pain crisis?

A
  1. hand-foot syndrome : dactylitis of hands/feet
  2. acute chest syndrome
  3. priapism

(stroke, retinopathy, blindness)

70
Q

What is sequestration crisis (seen in sickle cell patients)?

A

massive entrapment of sickled cells in spleen → rapid splenomegaly → hypovalemia → shock

71
Q

Chronic effects of sickle cell disease (2)

A
  1. renal injury: hyposthenuria (inability to concentrate urine)
  2. Infection: encapsulated organisms (H. flu, P. pneumo) → septicemia, meningitis
72
Q

sickle cell : tx

A

hydroxyurea (DNA synthesis inhibitor)

(increases HbF (a2g2) & decreases inflammation)

73
Q
A

“Autoinfarcted” splenic remnant in sickle cell disease

74
Q
A

Spleen in sickle cell disease (low power). Red pulp cords and sinusoids are markedly congested; between the congested areas, pale areas of fibrosis resulting from ischemic damage are evident

75
Q
A

Splenic sinusoids dilated and filled with sickled red cells

76
Q

_____ is a quick calculation to rule in HS.

A

MCHC/MCV >0.36

77
Q

Polyspecific antibody

A

specific to more than 1 antigen (anti-human Ig)

(screening test used to do Coombs testing: Anti-IgM, IgG, CD3)

Blood & Lymph (29 decks)

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