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Flashcards in 13. Hematology Deck (20)
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1
Q

What is the purpose of B12?

A

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

2
Q

What does B12 do with the methyl group from THF?

A

Gives it to homocysteine to make methionine

3
Q

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

A

High

4
Q

What is the most common cause of elevated homocysteine?

A

Folate deficiency

5
Q

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

A

Thrombocytosis and MI

6
Q

What is a specific test for B12 deficiency?

A

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

7
Q

What is the purpose of R factor?

A

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

8
Q

What makes intrinsic factor?

A

Parietal cells

9
Q

Where is B12-IF complex absorbed?

A

Terminal ileum

10
Q

Where is folate absorbed?

A

Jejunum and ileum

11
Q

What drug causes folate deficiency because it inhibits intestinal conjugase?

A

Phenytoin

12
Q

Why are alcoholics at increased risk of folate deficiency?

A

Alcohol blocks absorption of folate

13
Q

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

A

Hypersegmented neutrophils

14
Q

How do we differentiate between B12 and folate deficiency?

A

Neuro exam - neurological deficits in B12 deficiency

15
Q

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

A
  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
Q

What infection is most associated with aplastic anemia?

A

Hepatitis C

17
Q

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

A

Parvo B19

18
Q

How do we get extravascular hemolysis?

A

Macrophage takes RBC out of the blood vessel

19
Q

What’s the end product of a phagocytosed RBC?

A

Unconjugated bilirubin

20
Q

What clinical finding do we see in extravascular hemolysis?

A

Jaundice