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Week 23: Anemia > Iron and Other Supplements > Flashcards

Flashcards in Iron and Other Supplements Deck (21)
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1

How much iron is stored in
1. Hemoglobin
2. Liver

1. 2/3
2. 1/3

2

What is the problem with free iron interacting with molecular oxygen

Can generate free radicals

3

4 key tissues involved in iron metabolism

Intestine (duodenum) - absorption
Liver - regulation and storage
Bone marrow - utilization
Reticular endothelial system - recycling, storage

4

What percentage of iron is conserved? How much iron do men and women need a day?

95% of iron is conserved for future use
1 mg/day for men and post menopausal women
2 mg/day for women during repro years
4 mg/day for pregnant women

5

What form of iron is
1. Ferric
2. Ferrous

1. 3+
2. 2+

6

Absorption of iron through the duodenal enterocyte

Fe3+ is reduced to Fe2+ on the apical surface by ferric reductase
Fe2+ enters the cell via DMT1
Stored inside the cell as ferritin
Exits the cell via ferroportin
Hephaestin is involved in oxidation from 2+ to 3+

7

4 steps of the RBC turnover cycle

RBCs in bloodstream
Broken down inside macrophages to free the iron
Binds transferrin for travel
Most goes to bone marrow for new RBC production

8

How is iron bound to transferrin taken into cells

2 transferrin molecules (each with 2 Fe) bind to the transferrin receptor
Endocytosed
Acidified endosome causes release
Fe pumped out of endosome via DMT1
Fe bound to ferritin in cells, some binds to hemosiderin for longer term storage

9

2 ways iron is stored in cells

Ferritin
Hemosiderin

10

Hepcidin (how does it work, what is it produced by, levels in high or low iron states)

Key regulator of iron metabolism
Produced by the liver
Acts by inhibiting iron efflux out of intestinal, RE, and liver cells
Iron deficiency = levels drop
Iron overload = levels rise

11

How does hepcidin change in
1. Increased circulating iron
2. Inflammation
3. Erythropoiesis and hypoxia

1. Increase
2. Increase
3. Decrease

12

3 main causes of iron deficiency

Blood loss (main one)
Iron-poor diet
Malabsorption

13

In iron deficiency, is
1. Serum iron
2. Serum transferring (TIBC)
3. % saturation of transferrin
4. Ferritin
5. Free erythrocyte protoporphyrin
Low or high?

1. Low
2. High
3. Low
4. Low
5. High

14

In iron deficiency, is
1. Hb
2. MCV
3. Mean corpuscular Hb
4. Platelet count
low or high?

1. Low
2. Low
3. Low
4. High

15

Hemochromatosis

Genetic disorder (autosomal recessive)
Patients absorb 4 mg or more of iron per day
Iron deposition in parenchymal cells of liver, heart, pancreas, and other tissues

16

In hemochromocytosis, is
1. Serum iron
2. Serum transferring
3. % saturation of transferring
4. Ferritin
high or low?

1. High
2. Low
3. High
3. High

17

Vitamin B12 is a cofactor in which 2 biochemical reactions?

Homocysteine to methionine (generates THF)
Methylmalonyl CoA to succinyl CoA

18

Role of folate

Also a cofactor
Required to synthesize dTMP (precursor for DNA synthesis)

19

Results of B12 and/or folate deficiency

Most common cause of megaloblastic anemia
Erythroblasts in bone marrow show delayed maturation of nucleus relative to cytoplasm
DNA synthesis is defective
Circulating RBCs are macrocytic, with marked variations in size and shape

20

4 causes of B12 deficiency

Poor nutrition
Pernicious anemia (no IF)
Total or partial gastrectomy (no cells to make IF)
Intestinal disease

21

4 causes of folate deficiency

Poor nutrition (esp alcoholics)
Increased utilization (pregnancy/lactation, malignancy, inflammation, hemolytic anemia)
Intestinal disease
Drug-induced (ex: anticonvulsants)