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Mercy CLS 6: Hematology > 8) Macrocytic anemias > Flashcards

8) Macrocytic anemias Flashcards

1
Q

asynchronous maturation of any nucleated cell type

A

megaloblastic

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2
Q

establishment of megaloblastic anemia requires…

A

BM exam

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3
Q

causes of nonmegaloblastic macrocytic anemias (5)

A
  • increased retics
  • hypothyroidism
  • alcoholic liver disease
  • nonalcoholic liver disease
  • aplastic anemia/refractory anemia
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4
Q

causes of megaloblastic anemias (4)

A
  • B12 deficiency
  • folate deficiency
  • chemotherapy with drugs that inhibit DNA synth
  • CDA
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5
Q

other name for B12

A

cobalamin

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6
Q

only vitamin exclusively synthesized by microorganisms

A

B12

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7
Q

2 functions of B12

A
  • synthesis of methionine from homocysteine, central reaction in DNA synth
  • coenzyme to make succinyl CoA from methylmalonic acid (MMA)
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8
Q

buildup of both homocysteine and MMA

A

B12 deficiency

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9
Q

buildup of homocysteine, but not MMA

A

folate deficiency

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10
Q

folate trap

A

B12 deficiency causes folate to leak out of cells

traps folate in methylated form

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11
Q

required for absorption of B12

A

intrinsic factor

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12
Q

carries B12 in plasma

A

transcobalamin I, II, or III

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13
Q

why is dietary B12 deficiency so rare?

A

body stores 2-5 mg which will last for several years

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14
Q

4 general causes of B12 deficiency

A
  1. pernicious anemia (PA)
  2. inadequate intake
  3. other malabsorption syndromes
  4. microbiological utilization
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15
Q

GI system effects related to B12 deficiency

A

gastric atrophy
atrophic gastritis
intrinsic factor decreased
abd pain, constipation, diarrhea

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16
Q

CNS effects related to B12 deficiency

A

decreased myelination
tingling, numbness, weakness of extremities
“megaloblastic madness”, irritability, memory loss

17
Q

B12 deficiency on PB

A

macro-ovalocytes
hypersegmented neutros
decreased platelets
normal retics
Howell Jolly bodies
Cabot rings

18
Q

BM effects related to B12 deficiency

A

megaloblastic erythroid hyperplasia
giant metamyelocytes
bands
karyhorrhexis

19
Q

why do signs of hemolysis (LD, bilirubin, haptoglobin) occur in B12 deficiency?

A

abnormal cells lyse in BM (intravascular hemolysis)

20
Q

diagnosis of pernicious anemia (5)

A
  • megaloblastic BM
  • achlorhydria (low gastric acid)
  • decreased B12
  • Schilling test (determines lack of IF)
  • Serum Ab tests for autoAb against IF, parietal cells
21
Q

pernicious anemia tx

A

IV or IM B12

folic acid (causes remission of sx, but does not reverse neuro sx)

22
Q

buck blind loop syndrome

A

cause of B12 deficiency where, post surgery, there is overgrowth of bacteria in SI, which utilize B12 before it can be absorbed

23
Q

infestation with this tapeworm can cause B12 deficiency

A

Diphyllobothrium latum

24
Q

active form of folate

A

tetrahydrofolate (THF)

25
Q

plays vital role in metabolism of nucleotides and amino acids

A

folate

26
Q

sources of folate

A

romaine, spinach, okra, broccoli
beans
brewer’s yeast

27
Q

boiling destroys…

A

folate

28
Q

4 causes of folate deficiency

A
  1. inadequate intake
  2. increased demand (pregnancy)
  3. inadequate absorption
  4. drugs (OC, anticoags, phenobarb, primidione, phenytoin, alcohol)
29
Q

good indicator of folate status over last 4 months

not affected by recent diet

A

RBC folate level

30
Q

signs of B12 deficiency absent in folate deficiency

A

CNS sx
pancytopenia

31
Q

diagnosis of folate deficiency

A
  • decreased serum folate
  • decreased RBC folate
  • FIGLU excretion following histidine administration (not done much anymore)
32
Q

how does B12 affect folate?

A

required to keep conjugated folate in the cells

deficiency may cause ↓ RBC folate and ↑ serum folate

33
Q

B12, serum folate and RBC folate all decreased

A

B12 + folate deficiency

Mercy CLS 6: Hematology (25 decks)

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