L23- Iron Metab & Its Disorders (#5)

Question 1

An average animal contains approx ____ mg of iron per poundi n the body, which is distributed in the following way: ____% for storage, ___% for use

Answer 1

10-20 mg

- 25% for storage, 75% in use

Question 2

Because animal cells and organism are unable to promote iron loss, the only way iron loss can be achieved is by _____

Answer 2

Bleeding

Question 3

How is iron homeostasis maintained?

Answer 3

By absorbing an amount of iron equivalent to that which is unwillingly lost daily

Question 4

Iron content of various foods and feeds can be divided into? (3 things and give mg/kg amounts)

Answer 4

• High iron (>50 mg/kg)
• Intermediate iron (10-50 mg/kg)
• Low iron (

Question 5

What are examples of high iron foods?

Answer 5

Organ meats, Brewer’s yeast, egg yolks, wheat germ

Question 6

What are examples of intermediate iron foods?

Answer 6

Muscle meat, fish, most green veggies and cereal

Question 7

What are examples of low iron foods?

Answer 7

Milk, milk products, and non-green veggies

Question 8

What are the 3 forms that animal dietary iron exists in?

Answer 8

1. Heme iron
2. Ferrous iron (non-heme iron)
3. Ferric iron (non-heme iron)

Question 9

The bioavailability of the dietary iron goes in what order?

Answer 9

Heme iron» Fe2+ > Fe3+

Question 10

Which dietary iron is mainly found in meat and is the most bioavailable form of dietary iron?

Answer 10

Heme iron

Question 11

_____ iron is the most abundant form of non-heme iron

Answer 11

Ferric iron

Question 12

What are two drawbacks of ferric iron?

Answer 12

• Insoluble at physiological pH

- Not very bioavailable

Question 13

Clinical note: Bioavailability is decreased in individuals with achlorhydria- what is this?

Answer 13

Decreased HCl levels from gastric juice

Question 14

Clinical note: ______ also diminish the iron availability by raising the gastric pH, leading to ferric aggregate formation

Answer 14

Antacids

Question 15

______ is soluble at physiological pH and is more bioavailable than ferric iron

Answer 15

Ferrous iron

Question 16

Meal composition can either or diminish _____ iron bioavailability

Answer 16

Non-heme

Question 17

______________ such as cysteine, sorbitol, and fructose increase iron absorption

Answer 17

Reducing molecules

Question 18

Vitamin C enhances iron availability in what 2 ways?

Answer 18

1. Vit C reduces ferric iron Fe3+ to ferrous Fe2+

2. Vit C, as well as AA and glucose, can form complexes with iron. Iron complexes increase bioavail of ferrous iron

Question 19

What other two things are enhancers of iron absorption besides reducing molecules?

Answer 19

• AA

- Acidic foods

Question 20

What are phytates, tannins, and phosphates and phosphoproteins, oxalate, and calium, zinc copper or mangages ions categorized as?

Answer 20

Inhibitors of iron absorption

Question 21

EXPLAIN. Dietary iron deficiency is rare in adult pets. However, young puppies and kittens are esp vulnerable to iron deficiency. Why?

Answer 21

Nursing animals are more susceptible to this problem because milk is low in iron. Hence, iron is needed for growth exceeds the supply avail from diet and body stores. However, it is very unlikely that iron deficiency would occur in post-weaning animals fed balanced meals

Question 22

EXPLAIN. In order to inc iron absorp in an iron deficient puppy, is it better to combine or to separate iron supplements and milk?

Answer 22

It would be better to separate them in order to minimize effect of calcium (inhibitor competing with iron) in iron absorption

Question 23

______ is a serum protein in charge of transporting iron through circulation

Answer 23

Transferrin

Question 24

What is the difference btwn absorption and uptake?

Answer 24

Absorption: refers to dietary iron moving thru enterocytes into circulation

Uptake: iron from circulation moving into cells in body tissues

Question 25

Where does iron absorption occur?

Answer 25

At the enterocytes of the duodenum and upper jejunum

Question 26

Clinical note: Surgical removal of any part of the duodenum and/or upper jejunum will _______ iron absorption

Answer 26

Decrease

Question 27

Why is unbound iron toxic?*

Answer 27

Because it non-enzymatically catalyzes the formation of highly destructive hydroxyl radical (OH)- this is called the Fenton reaction

Question 28

Why are hydroxyl radicals so destructive?

Answer 28

They have the potential to damage virtually every cellular component

Question 29

Transferrin is an abundant serum protein which binds ferric iron with high affinity, thus causing what 3 things?

Answer 29

1. Solubilizes iron 2. Attenuates iron reactivity 3. Delivers iron to sites of use and storage

Question 30

What is apotransferrin?

Answer 30

When transferrin is NOT bound to iron

Question 31

When transferrin is bound to one Fe3+ atoms, it is called?

Answer 31

Diferric transferrin

Question 32

What are transferrin receptors (TfR)?

Answer 32

A plasma membrane protein which binds and mediates the cellular uptake of the iron-transferrin complex

Question 33

What is another form of ferritin that has been partially modified in lysosomes?

Answer 33

Hemosiderin

Question 34

What are the 3 involuntary mechanism to lose iron?

Answer 34

1. Sloughing off skin and mucosal cells 2. Sweat, hair and nail loss 3. Bleeding

Question 35

How much mg of iron does one ml of blood contain?***

Answer 35

0.5 mg of iron!

Question 36

EXPLAIN AND CALCULATE. A mixed breed dog affected with a bleeding neoplasm is losing 10 ml of blood daily. How long would it take to deplete his iron stores? Assume his initial iron stores are 1,000 mg, average diet and constant blood loss.

Answer 36

- There is 0.5 mL of iron per mL of blood. - 10 mL blood lost per day (0.5 mg Fe/mL blood * 10 mL= 5 mg Fe lost per day) - 1000 mg Fe stores/ 5 mg lost per day = 200 days to deplete iron stores!!

Question 37

What are the 4 lab assessment/tests of iron?

Answer 37

1. Serum iron 2. TIBC 3. % Transferrin saturation 4. Serum ferritin

Question 38

What are the 3 primary cause of iron defeciencies?

Answer 38

1. Nutritional 2. Inadequate absorption 3. Chronic blood loss

Question 39

Out of the 3 primary causes of iron deficiency, which one would be the most common in small animals?

Answer 39

Chronic blood loss

Question 40

Treatment of iron deficiency requires _____? (dont overthink)

Answer 40

Iron supplements

Question 41

Predict the following test results in case of iron deficiency patient (4 tests)

Answer 41

1. Serum iron= decreased 2. TIBC = increased 3. % transferrin saturation = decreased 4. Serum ferritin = decreased

Question 42

In an animal with iron deficiency anemia, the levels of serum ferritin (iron stores) are inversely proportional to __________________ lvls

Answer 42

Serum transferrin lvls

Question 43

When iron levels are high in an animal with iron deficiency, what things should we take note of?

Answer 43

Make note of if there are changes in: ferritin, transferrin Ferritin: is high in order to store the iron Transferrin: is low

Question 44

In the four tests I want to know whats that all about serum iron, TIBC, % Transferrin saturation, and Serum ferritin. What are the patient results after seeing that iron is unavailable?

Answer 44

Serum iron: dec TIBC: dec % Transferrin sat: Dec Serum ferritin: Incr

Question 45

In the four tests I want to know whats that all about serum iron, TIBC, % Transferrin saturation, and Serum ferritin. What are the patient results after seeing that iron is unavailable?

Answer 45

Serum iron: inc TIBC: dec % Transferrin sat: inc Serum ferritin: Incr

Question 46

Serum ferriton (iron stores) are ________ to Tf (TIBC) lvls

Answer 46

Inversely proportional

Question 47

In a dog with iron overload, what occurs to Ferritin and TIBC (Tf)?

Answer 47

``` Increased ferritin Decreased TIBC (Tf) ```

Question 48

Why is iron so important for animals?

Answer 48

It is an essential micronutrient for all living organisms