Iron and Other Supplements

Question 1

How much iron is stored in

1. Hemoglobin
2. Liver

Answer 1

1. 2/3

2. 1/3

Question 2

What is the problem with free iron interacting with molecular oxygen

Answer 2

Can generate free radicals

Question 3

4 key tissues involved in iron metabolism

Answer 3

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

Question 4

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

Answer 4

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

Question 5

What form of iron is

1. Ferric
2. Ferrous

Answer 5

1. 3+

2. 2+

Question 6

Absorption of iron through the duodenal enterocyte

Answer 6

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+

Question 7

4 steps of the RBC turnover cycle

Answer 7

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

Question 8

How is iron bound to transferrin taken into cells

Answer 8

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

Question 9

2 ways iron is stored in cells

Answer 9

Ferritin

Hemosiderin

Question 10

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

Answer 10

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

Question 11

How does hepcidin change in

1. Increased circulating iron
2. Inflammation
3. Erythropoiesis and hypoxia

Answer 11

1. Increase
2. Increase
3. Decrease

Question 12

3 main causes of iron deficiency

Answer 12

Blood loss (main one)
Iron-poor diet
Malabsorption

Question 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?

Answer 13

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

Question 14

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

Answer 14

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

Question 15

Hemochromatosis

Answer 15

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

Question 16

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

Answer 16

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

Question 17

Vitamin B12 is a cofactor in which 2 biochemical reactions?

Answer 17

Homocysteine to methionine (generates THF)

Methylmalonyl CoA to succinyl CoA

Question 18

Role of folate

Answer 18

Also a cofactor

Required to synthesize dTMP (precursor for DNA synthesis)

Question 19

Results of B12 and/or folate deficiency

Answer 19

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

Question 20

4 causes of B12 deficiency

Answer 20

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

Question 21

4 causes of folate deficiency

Answer 21

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