13. Hematology Flashcards Preview

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Flashcards in 13. Hematology Deck (20):
1

What is the purpose of B12?

Takes the methyl group of tetrahydrofolate; THF can't help make DNA if it's methylated

2

What does B12 do with the methyl group from THF?

Gives it to homocysteine to make methionine

3

What is the serum homocysteine level in B12/folate deficiency?

High

4

What is the most common cause of elevated homocysteine?

Folate deficiency

5

What does increase in homocysteine levels put you at risk for?

Thrombocytosis and MI

6

What is a specific test for B12 deficiency?

Elevated methylmalonic acid because B12 is a cofactor for the conversion of methylmalonyl coA to succinyl coA

7

What is the purpose of R factor?

Protects B12 from being destroyed in the stomach; binds in saliva

8

What makes intrinsic factor?

Parietal cells

9

Where is B12-IF complex absorbed?

Terminal ileum

10

Where is folate absorbed?

Jejunum and ileum

11

What drug causes folate deficiency because it inhibits intestinal conjugase?

Phenytoin

12

Why are alcoholics at increased risk of folate deficiency?

Alcohol blocks absorption of folate

13

What is the hallmark histology for B12 and folate deficiency megaloblastic anemias?

Hypersegmented neutrophils

14

How do we differentiate between B12 and folate deficiency?

Neuro exam - neurological deficits in B12 deficiency

15

What are the 3 causes of B12 deficiency that we can check with a Schilling test?

1. Pernicious anemia - get radiolabeled B12 when we give with intrinsic factor
2. Bacterial overgrowth - get radiolabeled B12 when we give antibiotics
3. Pancreatitis - get radiolabeled B12 when we give pancreatic enzymes

16

What infection is most associated with aplastic anemia?

Hepatitis C

17

What infection is most associated with decrease in just RBC's?

Parvo B19

18

How do we get extravascular hemolysis?

Macrophage takes RBC out of the blood vessel

19

What's the end product of a phagocytosed RBC?

Unconjugated bilirubin

20

What clinical finding do we see in extravascular hemolysis?

Jaundice