Dietary Iron in the body

Question 1

What happens to iron that isn’t absorbed?

Answer 1

Released in faeces

Question 2

What happens to iron that is absorbed?

Answer 2

Goes into the body

Question 3

How is iron thats been absorbed transported around the body?

Answer 3

On transferrin (Fe3+)

Question 4

Where will iron that is being transported around the body on transferrin eventually end up going?

Answer 4

To a site of erythropoiesis

Question 5

Where does erythropoiesis mainly occur?

Answer 5

In the bone marrow

Question 6

What is phagocytosis?

Answer 6

old, damaged, or abnormal RBCs are engulfed and broken down by specialised immune cells called reticuloendothelial cells (RE cells)

Question 7

Where are RE cells mainly found?

Answer 7

Mainly found in tissues and organs involved in filtration, immune response, and blood cell recycling
e.g. liver, spleen, bone marrow

Question 8

What happens to RBC’s that have been broken down?

Answer 8

• That which is not needed is stored as ferritin which can end up in the blood
• Others will be reused to make new haemoglobin (recycling)

Question 9

Why is recycling of iron so important?

Answer 9

We have a relatively small intake compared to the amount of iron needed to replace our RBC’s and help the body to function

Question 10

How many iron ions can transferrin carry?

Answer 10

2 (has two lobes/sites)
- TIBC is about how many of these sites don’t have iron on them

Question 11

If ferritin is stored in high amounts in places like the liver, why do we not need a liver biopsy to measure iron status? Wouldn’t serum Fe be lower?

Answer 11

A proportionate amount of ferritin leaks into the blood stream whilst being stored

Question 12

What do soluble transferrin receptors do when transferrin carrying iron comes past a tissue?

Answer 12

The hungrier a tissue/cell (the more it needs iron) the more receptors it is going to put out on its surface to pick up more iron

Question 13

How do we measure soluble transferrin receptors in blood samples?

Answer 13

Luckily, some of these receptors end up in the circulation so we can pick that up

Question 14

Transferrin saturation vs. TIBC when iron status is low

Answer 14

When iron status is low, there will be few spots taken up on the transferrin molecules creating low transferrin saturation. However, since there is much availability, TIBC will be high!