8) Macrocytic anemias

Question 1

asynchronous maturation of any nucleated cell type

Answer 1

megaloblastic

Question 2

establishment of megaloblastic anemia requires…

Answer 2

BM exam

Question 3

causes of nonmegaloblastic macrocytic anemias (5)

Answer 3

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

Question 4

causes of megaloblastic anemias (4)

Answer 4

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

Question 5

other name for B12

Answer 5

cobalamin

Question 6

only vitamin exclusively synthesized by microorganisms

Answer 6

B12

Question 7

2 functions of B12

Answer 7

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

Question 8

buildup of both homocysteine and MMA

Answer 8

B12 deficiency

Question 9

buildup of homocysteine, but not MMA

Answer 9

folate deficiency

Question 10

folate trap

Answer 10

B12 deficiency causes folate to leak out of cells

traps folate in methylated form

Question 11

required for absorption of B12

Answer 11

intrinsic factor

Question 12

carries B12 in plasma

Answer 12

transcobalamin I, II, or III

Question 13

why is dietary B12 deficiency so rare?

Answer 13

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

Question 14

4 general causes of B12 deficiency

Answer 14

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

Question 15

GI system effects related to B12 deficiency

Answer 15

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

Question 16

CNS effects related to B12 deficiency

Answer 16

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

Question 17

B12 deficiency on PB

Answer 17

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

Question 18

BM effects related to B12 deficiency

Answer 18

megaloblastic erythroid hyperplasia
giant metamyelocytes
bands
karyhorrhexis

Question 19

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

Answer 19

abnormal cells lyse in BM (intravascular hemolysis)

Question 20

diagnosis of pernicious anemia (5)

Answer 20

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

Question 21

pernicious anemia tx

Answer 21

IV or IM B12

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

Question 22

buck blind loop syndrome

Answer 22

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

Question 23

infestation with this tapeworm can cause B12 deficiency

Answer 23

Diphyllobothrium latum

Question 24

active form of folate

Answer 24

tetrahydrofolate (THF)

Question 25

plays vital role in metabolism of nucleotides and amino acids

Answer 25

folate

Question 26

sources of folate

Answer 26

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

Question 27

boiling destroys...

Answer 27

folate

Question 28

4 causes of folate deficiency

Answer 28

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

Question 29

good indicator of folate status over last 4 months not affected by recent diet

Answer 29

RBC folate level

Question 30

signs of B12 deficiency absent in folate deficiency

Answer 30

CNS sx pancytopenia

Question 31

diagnosis of folate deficiency

Answer 31

- decreased serum folate - decreased RBC folate - FIGLU excretion following histidine administration (not done much anymore)

Question 32

how does B12 affect folate?

Answer 32

required to keep conjugated folate in the cells deficiency may cause ↓ RBC folate and ↑ serum folate

Question 33

B12, serum folate and RBC folate all decreased

Answer 33

B12 + folate deficiency