13 Iron

Question 1

Homeostasis of iron regulated mostly by?

Answer 1

Absorption

hard to excrete iron

Question 2

How much iron do we need?

Answer 2

less than 5 grams

- trace minerals

Question 3

Iron ionic states

Answer 3

Oxidized
- Ferric Iron Fe3+

Reduction
- Ferrous Iron Fe2+

serves as a cofactor for oxidation/reduction reactions

Question 4

Absorption of iron determined by?

Answer 4

1. “content” of diet
2. “bioavailability” of dietary iron
   - heme vs non-heme
3. capacity of mucosal cells to absorb iron (typically non heme)
   - absorption enhancers and inhibitors
   - iron status

Question 5

Food sources of diet

Answer 5

red meats 
fish
poultry
eggs 
legumes
dried fruits

Question 6

heme vs non heme

Answer 6

Heme

• animals
• 10% daily intake
• 25-35% absorbed (constant rate)

Non Heme

• plant and animals
• 90% daily intake
• only 2-20% absorbed
• rate depends on other factors

Question 7

Factors affecting non heme absorption

Answer 7

MFP factor (meat fish poultry)
- provides heme but also promotes non heme absorption
Vit C
Gastric Acid
lactic, malic, tartaric acid

Question 8

What ionic state of iron is better absorbed?

Answer 8

Ferrous Acid

- acids donate hydrogen to Ferric to reduce it to ferrous

Question 9

Iron absorption inhibitors

Answer 9

phytate (grains, beans, nuts, potatoes)

polyphenols

• fruits, veges coffee, tea, wine
• Vit C inhibits this effect***

EDTA (food additives)

oxalate (spinach, rhubarb)

Question 10

4 types of proteins that require iron for their synthesis

Answer 10

1. heme proteins (and non)
2. iron sulfur cluster proteins
3. proteins with single iron atoms
4. proteins with oxygen bridged iron

Question 11

Iron transport proteins

Answer 11

Transferrin
Transferrin Receptor
Others… not important

Question 12

Transferin

Answer 12

Transport protein

• iron is part of the protein
• binding and release result of conformational change
• open without iron
• closed with iron

Question 13

Transferrin Receptor

Answer 13

in cell membranes, allows iron intake

Question 14

Iron storage proteins

Answer 14

Ferritin

• house large amounts of iron in soluble, non toxic, bioavailable form
• best way to assess iron stores

Hemosiderin
- increase in iron overload

Question 15

% world iron deficient

Answer 15

30%

Question 16

Symptoms of iron deficiency

Answer 16

anemia
- fatigue

in children

• cognative performance in children
• increase lead poisoning

Question 17

Stages of iron deficiency

Answer 17

1. iron depletion
2. iron deficient erythropoiesis
3. iron deficiency anemia

Question 18

1st stage of iron deficiency

Answer 18

iron depletion

• low iron stores
• decrease serum ferratin
• normal transport iron and Hb

Question 19

2nd stage of iron deficiency

Answer 19

Iron Deficient Erythropoiesis

• complete exhaustion iron stores
• low blood iron conc.
• less iron delivered to erythropoietic cells
• increase erythrocyte protoporphyrins
• hemoglobin usually normal

Question 20

3rd stage of iron deficiency

Answer 20

Iron Deficiency Anemia

• complete exhaustion iron stores and declining circulating iron
• reduced HB in RBCs

Question 21

Biochemical signs of iron deficiency at various stages

Answer 21

v ferratin
v iron
v transferrin saturation
^ erythrocyte protoporphryin 
v hemoglobin

• all blood concentration

Question 22

iron overload

Answer 22

Hemochromatosis

• hereditary
• more prelevent in males
• increased iron absorption
• transferrin hypersaturation
• can cause organ damage
• treatment involves phlebotomy

Question 23

What vitamin to avoid when have iron overload

Answer 23

vitamin C