Macrocytic anemia Flashcards Preview

2nd U2 Path > Macrocytic anemia > Flashcards

Flashcards in Macrocytic anemia Deck (31):
1

Anemia with an MCV > 100um3…

Macrocytic anemia

2

What are the 2 most common causes of macrocytic anemia?

Folate deficiency
Vitamin B12 deficiency

3

What must be removed from serum methyltetrahydrofolate (THF) in order for it to participate in DNA synthesis?

Methyl group must be transferred to Vitamin B12

4

Where is the methy group transferred to from methyltetrahydrofolate to allow THF to participate in DNA synthesis?

Vitamin B12

5

Where does Vitamin B12 transfer the methyl group to produce methionine?

Homocysteine

6

What leads to megaloblastic anemia?

Impaired division and enlargement of RBC precursors

7

Hypersegmented neutrophils occur with macrocytic anemia. What causes there to be produced?

Impaired division of granulocytic precursors

8

What are some causes of macrocytic anemia without megaloblastic change?

Alcoholism
Liver disease
Drugs (5-FU)

9

Where does the absorption of folate occur?

Jejunum

10

What are some common causes of folate deficiency?

Poor diet
Increased demand
Folate antagonists

11

Macrocytic anemia can be caused by a poor diet. Who are the two most common groups of people who present with a folate deficiency due to poor diet?

Alcoholics
Elderly

12

What are some causes of increased demand for folate, causing a folate deficiency?

Pregnancy
Cancer
Hemolytic anemia

13

What is a common drug that is a folate antagonist causing a folate deficiency?

Methotrexate—inhibits dihydrofolate reductase

14

What changes are seen with RBCs with folate deficiency?

Macrocytic RBCs

15

What changes are seen with neutrophils with folate deficiency?

Hypersegmented neutrophils (> 5 lobes)

16

With respect to folate levels and serum homocysteine, what are the laboratory values seen with a folate deficiency?

Serum folate—decreased
Homocystein—increased

17

What is a normal finding seen with folate deficiency with helps differentiated it from a different cause macrocytic anemia?

Methylmalonic acid

18

What is bound to vitamin B12 to allow it to be carried to through the stomach?

R-binder

19

What cause the detachment of R-binder from vitamin B12?

Pancreatic proteases

20

Where does the detachment of R-binder from vitamin B12 occur?

Duodenum

21

What binds vitamin B12 in the small bowel allowing absorption of B12 by the ileum?

Intrinsic factor

22

What cells produce intrinsic factor, which binds vitamin B12 to allow absorption in the ileum?

Gastric parietal cells

23

What is the most common cause of vitamin B12 deficiency?

Pernicious anemia

24

Autoimmune disorder involving destruction of parietal cells, which leads to intrinsic factor deficiency?

Pernicious anemia

25

Besides pernicious anemia, what are some other causes of vitamin B12 deficiency?

Pancreatic insufficiency
Damage to terminal ileum
Dietary deficiency (RARE, except in vegans)

26

What are the two most common causes of damage to the terminal ileum, which causes a vitamin B12 deficiency?

Crohn disease
Diphyllobothrium latum (tapeworm)

27

What are changes that occur to RBCs with vitamin B12 deficiency?

Macrocytic RBCs

28

What changes occur to neutrophils with vitamin B12 deficiency?

Hypersegmented neutrophils

29

Why is poor proprioception and vibratory sensation, along with spastic paresis seen with vitamin B12 deficiency?

Vitamin B12 is cofactor for the conversion of methylmalonic acid to succinyl CoA

With Vitamin B12 deficient→ there is an increased level of methylmalonic acid impairing the spinal cord myelinization

30

With respect to serum Vitamin B12, serum homocysteine, and Methylmalonic acid, what are the laboratory results seen with a vitamin B12 deficiency?

Serum Vitamin B12→ decreased
Serum homocysteine→ Increased
Methylmalonic acid→ increased

31

What laboratory finding allows differentiation between a folate deficiency and a Vitamin B12 deficiency?

Methylmalonic acid levels

Normal with folate deficiency

Elevated with vitamin B12 deficiency