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Flashcards in Macrocytic Anemia Deck (28):
1

three pathological mechanisms of macrocytosis

too many immature RBC

membrane too large for Hb content

defect n DNA synthesis and nucleus of erythrobast divides fewer times than cyto

2

not real macrocytosis, but will read that way

shifting of immature cells from marrow-->peripheral blood (reticulocytosis)--this is considered NONmegaloblastic

3

Megaloblastic anemias

B12 def
folate def
medications (azt, hydroxyurea)

4

reticulocytoss

action of epo to correct anemia causes RBC to skip divisons in an effort to push out into periphery

5

vitamin b12 and folate

required for thymdylate and purine synthesis therefore their deficiency result in retarted DNA synthesis

6

RNA synthesis

even though DNA synthesis is impared, RNA synthesis is unaffected-->more cytoplasmic components in a slowly dividing cell

7

vit b12 rxn (2)

Vit B12 + homocysteine--> THF -->methionine--> purines/pyrmidines

formation of succinyl coa

8

blocking vitamin b12 leads to excess

MMA, homocysteine

9

b12 deficency by

cannot be produced by human body and only comes from animal byproducts (so vegans have issues)..takes a long time to develop

10

vit b12 absorption mech

in stomach binds to HAPTOCOIRIN-->in duo pancreatic proteases cleave-->binds to IF which is released by parietal cells-->absorbed by terminal ileum

11

defect in intrinsic factor

pernicious anemia
--autoantibodies to gastric pareital cells which make intrinsic factor

12

effects of vitamin B12 deficiency

hematological effects- anemia and pancytopenia
neurological disorders- gait/paresthesias/numbness, cog disorders (due to demyelin)
developmental effects

13

schilling test

check to see if vit b12 is due to lack of intrinsic factor

14

treatment B12 deficiency

inject B12 supplementation
-high dose oral sometimes an option-- daily/weekly at first than monthly

15

sources of folate

leafy vegetables -- spinach, turnip greens, lettuces, dried beans, peas, cereal, sunflower seeds

16

folate's job

synthesize DNA bases (thymidine) needed for DNA replicatio

17

causes of folate deficiency

decrease in oral intake
decreased absorption in duodenum and ileum
drugs
increased utlization

18

reasons for decreased oral intake

alcoholism
depression
nursng home pts
overcooked food

19

reasons for decreased absorption

sprue
inflam bowel disease
infiltrative bowel disease
short bowel syndrome

20

drugs that decrease abs

methotrexate
trimethoprim
ethanol
phenytoin

21

why increased utilization of folic acid

pregnancy
lactation
chronic hemolysis
exfoliative dermatitis

22

only clinical difference between folate and B12 def

do not get neuro deficitis w/ folate

23

why you shouldnt give folate when you see megaloblastic anemia

if the patient lacks B12, folic acid is potentially capable of precipitating subacute combined degeneration of cord

24

vit b12 tests vs folate tests

folate (normal MMA, inc homocysteine)
B12 (inc MMA, inc homocysteine)

25

folate def develops over

4-5 months (vs 2-12 years for vt b12)

26

other possibilities for macrocytic anemia

TSH
alcohol hx
Liver issues

27

why does alcoholism play a role?

malnourished
liver dsiease- increases lipid deposition on red cell membranes
acetaladhyde induces membrane changes in red cell precursors and circulating red cells

28

b12 or folate deficiency show___ on peripheral blood smear

hypersegmented neutrophils