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Cardiopulmonary I > Vitamin B12/Folate - White > Flashcards

Vitamin B12/Folate - White Flashcards

1
Q

Deficiency of vitamin B12 and folate can cause

A

Severe anemia called megaloblastic anemia

-prevents adequate amounts of DNA

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2
Q

Megaloblastic anemia and DNA synthesis

A

Results in retarded synthesis of DNA

-continual dna synthesis is required for production of numerous erythroblasts

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3
Q

Megaloblastic anemia

A

Retarded synthesis of DNA

Erythroid precursors are stuck in the bone marrow - results in megaloblastic, hyperplasia marrow smears

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4
Q

Macrocytic anemia lab values

A

MCV > 100fl (normal 80-100)
Normal Hb content in relation to size
Blood smear shows macrocytic, normochromic cells
RBC volume is elevated

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5
Q

Macrocytic anemia clinical presentation

A

Lethargy, weakness, yellow or waxy pallor, loss of weight and appetite, diarrhea

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6
Q

Megaloblastic macrocytic anemia bone marrow

A

Large erythroblasts

Hypersegmented neutrophils - 5 vs 3

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7
Q

Megaloblasts

A

Large erythroid precursors
Decrease in mitotic divisions
Nuclear development delayed
Cytoplasmic volume continues to expand

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8
Q

Hyperplasia

A

Many cells

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9
Q

Megaloblastic

A

Big cells

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10
Q

Clinical presentation of megaloblastic macrocytic anemia

A

Neurological sxs: peripheral neuropathy
-pins and needles
-loss memory
Rare - megaloblastic madness

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11
Q

No folate

A

Impaired DNA synthesis

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12
Q

3 parts of folic acid

A

Pteridine
PABA
Chain of glutamic amino acid

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13
Q

DHF

A

Dietary folic acid

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14
Q

DHF reduced to ______ by _____

A

THF by dihydrofolate reductase

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15
Q

What is the active form of DHF

A

THF

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16
Q

Function of THF

A

Transfer carbon units

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17
Q

Folate found in

A

Most foods

-eggs, milk, yeast, leavy

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18
Q

Most common cause of folate deficiency is

A

Inadequate dietary intake

-usually poor and elderly

19
Q

Folate deficiency most common

A 
Poor
Elderly
Alcoholics - little folate
Pregnancy
Drugs
20
Q

Daily folate

A

50 ug
50-80% is ingested
Absorbed in jejunum
Liver stores 5 to 10 mg

21
Q

Folate trap

A

If no folate, trapped in N5-methyl-THF

22
Q

Folic acid in intestine reduced

A

to N5-methyl-THF

23
Q

The primary circulating form of THF in blood stream is?

A

N5-methyl-THF

24
Q

2 proteins needed for transport of folate into cells

A

N5-methyl-THF concentrates folates into vesicles

Membrane folate transporter - transfers N5-methyl-THF from the vesicles to the cytosol

25
Q

N5-methyl-THF need to be ______ to enter folic acid cycle as THF

A

De-methylated

26
Q

N5-methyl-THF requires _________ to become demethylated?

A

Vitamin B12 (cobalamin)

27
Q

If B12 not available

A

then folate stuck as N5-methyl-THF

-lots of folate, but can not use it

28
Q

Recommended daily allowance B12

A

3ug
Animal products NOT plants
-microorganisms make it

29
Q

Majority of B12 deficiency from

A

Lack of a protein called intrinsic factor

85%

30
Q

Dietary B12 binds to proteins called

A

R-binder proteins

Made by parietal cells

31
Q

Intrinsic factor

A

Made by parietal cells

Carries B12 ro ileum where receptors bring B12 into body

32
Q

Pernicious anemia

A

Vit B12 def due to lack of intrinsic factor
Gastic mucosa destroyed through auto-immune mechanism
Decreased intrinsic factor

33
Q

Type of megaloblastic macrocytic anemia

A

Pernicious anemia

34
Q

Pernicious anemia lab results

A

Serum folate < 3 ng/ml

Serum B12 < 350 pg/ml

35
Q

Schilling test

A

Given oral dose of 57Co-labeled B12
Injection of 1000 ug unlabeled B12
Collect urine 24 hours

36
Q

Schilling test - radioactive B12 absent

A

Cobalamin (B12) not absorbed

Pernicious anemia

37
Q

Schilling test - radioactive B12 present

A

Normal absorption of B12 and radioactivity shows in urine

B12 deficient diet is answer

38
Q

Schilling Test Part 2

A

Add intrinsic factor

39
Q

After Schilling part 2, radioactive B12 present

A

Pernicious anemia due to lack of intrinsic factor

40
Q

Folate deficiency treatment

A

Alter diet

41
Q

Pernicious anemia treatment

A

B12 injections monthly

42
Q

Deficiency of B12 also caused by

A

Surgical removal of stomach or Crohn’s

43
Q

If pt presents with lethargy, weakness, loss of appetite, low Hb%, low RBC count, low serum folate of 0.1 ng/ml and high MVC of 140 fl. Most likely diagnosis?

A

Megaloblastic macrocytic anemia

Cardiopulmonary I (34 decks)

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