Iron

Question 1

Cytochrome P450

Answer 1

An an iron enzyme used in first line of defense against toxins
Oxidizes: Caffeine, acetaminophen, nicotine, diazepam. aniline and benzene

Question 2

When is iron most needed?

Answer 2

Periods of growth, blood loss (mensuration),

Question 3

How much Iron is lost a day & from where

Answer 3

1-2mg – GIT, skin, Epithelial lining

Question 4

How is iron involved in DNA transcription

Answer 4

Ribonucleotide reductase (converts ribonucleotides to deoxyribonucleotides) uses oxygen-bridged iron for stability.

Therefore:
Too little iron = Can’t properly syn DNA
Too much = Free radicals affect DNA

Question 5

RDA for Adult Men and Women and Pregnant women

Answer 5

Men Always 8
Women: 18
Pregnant women: 27

Question 6

RDA for Veg and Oral Contraceptive women (why?)

Answer 6

Veg = 1.8x higher (~32) B/c non-heme iron isn’t as bioavail
Oral Contraceptives = 10.9mg B/c there is less blood loss

Question 7

Why is the AI for infants iron consumption so low?

Answer 7

0.27g ,It’s based off of healthy breastfed infants, which have high needs but really high bioavailability through source Lacto-ferrin

Question 8

What sources of Food would provide enough iron within one serving?

Answer 8

Peanut butter, Claims, Beef liver (For all)
Claims only for Women 19-50

Question 9

What form of iron is in dairy products?

Answer 9

low iron, non-heme

Question 10

Heme Iron absorption

Answer 10

Little regulation, Through hcp 1, hydrolyzed to inorganic ferrous Fe and protoporphyrin, Also hydrolyzed in stomach and Small I (25% absorbed)

Question 11

Non-heme absorption

Answer 11

Hydrolyzed from food components in the stomach, Fe2+ taken up by DMT1, Fe3+ can reduced into Fe2+ on BBM or turned into Fe(OH) which is insoluble = feces
17% absorbed

Question 12

Why does increasing acidity improve iron absorption?

Answer 12

Supplies more ways to reduce Fe3+ which would improve absorption

Question 13

What is iron balance determined by?

Answer 13

Iron absorption.

Question 14

Increased Iron absorption is a result of duodenal expression of

Answer 14

DCYTB - increase reduction of ferric to ferrous
DMT1 - increase transport into cell
Ferroportin - increase transport of ferrous iron out
All cell iron transporters for uptake and output

Question 15

When would there be an increased need for iron

Answer 15

pregnancy, erythropoiesis, hypoxia, iron deficiency

Question 16

Hepcidin

Answer 16

Binds ferroportin for degradation when body stores are high
- depletes expression of brush boarder transporters

Question 17

Hephaestin

Answer 17

Secreted by liver, oxidizes Ferrous to Ferric before apotransferrin transport

Question 18

Factors that increase iron absorption

Answer 18

Meat Factor protein (MFP - AA or other food used to increase non-heme
Vit C
Acids/Sugars - Ascorbic, citric, lactic, gastric
Use iron cookware

Question 19

Factors that decrease absorption

Answer 19

Phytates, polyphenols, soy
Acids: Oxalates (spinach, beets, rhubarb), Tannic
Minerals
EDTA
Vegan diet (10% absorbed)
Intraluminal factors (rapid transit time, malabsorption, gastric juice)

Question 20

Which salts absorb better in the diet Ferrous or ferric
(& examples)

Answer 20

Ferrous salts absorb better -

Ferrous salts: Lactate, fumarate, gluconate, citrate
Ferric salts: Sulfate, citrate

Question 21

Why is Calcium a concerning mineral for iron absop

Answer 21

shown to decrease activity of ferroportin

Question 22

Purpose of Chelators - examples?

Answer 22

Small molecules that bind metal ions
Main purpose: to bind and make iron unavailable
Increase (weak chelators protect iron from strong chelators): ascorbates + citrates
Decease (strong chelators): Tannins, phytates

Question 23

Endogenous chelator

Answer 23

Mucin = binds and improves absorption

Question 24

Desferrioxamine, deferasirox

Answer 24

Iron chelators that bind iron specifically. Used for iron excess therapy to protect the cell from toxicity

Question 25

Where is majority of Iron in the body + Rest

Answer 25

Functional iron ~78% Hb, Mb, Heme/N enzymes (Hemoglobin (2/3) –
Storage: 22% (Ferritin + hemosiderin)
Transport 0.001% - transferrin

Question 26

How is the need for iron 20mg a day but only ~15mg is required in the diet?

Answer 26

Turnover of Hb, ferritin, and hemosiderin accounts for 18mg/day
Though Diet calls for ~15mg/day only 1-2mg is actually absorbed

Question 27

TfR 1 vs TfR2

Answer 27

Receptors
1 = protein for transferring iron uptake, subject to regulation
2 = involved in regulation of hepcidin transcription / sensor of iron levels, not regulated

Question 28

Transferrin Saturation: Levels

Answer 28

30% saturated usually
<30 depleted iron stores
<15 iron deficient erythropoiesis
>60 dangerrr

Question 29

The difference between STEAP and DcytB

Answer 29

Both on apical side to reduce Fe3 to Fe2 before transport.
STEAP is endosomes
B is duodenal enterocytes

Question 30

What 3 nutrients are needed for Erythropoiesis, what stims?

Answer 30

Iron, folic acid, B12
Stim: Erythropoietin

Question 31

How does the body recycle RBC

Answer 31

RBC are recycled by mononuclear phagocytic system -
Lysed in lysosomes of macrophages - heme is broken down and iron exported into cytosol - exported from macrophages via ferroportin into plasma and reduced by ceruloplasmin - loaded onto transferrin

Question 32

How does the body respond to excess iron?

Answer 32

apotransferring and ceruloplasmin ensure that iron is immediately chelated to limit toxicity and free radicals

Question 33

Would transferrin increase during iron deficiency?

Answer 33

it may increase but not a good indicator because it’s more likely to show responses to diet

Question 34

sTfR

Answer 34

Expressed on cells in need of iron
- High mean iron is needed
- Can be overexpressed from inflammation, will decrease when RBC not needed

Question 35

IRE - Iron response elements

Answer 35

Active - when low iron, binds to restrict ferritin and increase TfR syn
Inactive - when iron is abundant, ferritin syn proceeds

Question 36

What are normal and deficient levels for Hb for M and F

Answer 36

Normal - M = 135-175. F= 120-160
Deficient - M = Less than 125. F = less than 110

Question 37

Answer 37

Question 38

Hemosiderin

Answer 38

Storage of iron within lysosomes