Iron Metabolism

Question 1

How can we alter the amount of iron in out bodies?

Answer 1

We have no method for excretion of Iron and so we must alter how much we absorb. For a typical adult this is 1-2mg a day.

Question 2

Where is the majority of active iron found in our bodies?

Answer 2

In haemoglobin and accounts for approx 200mg. 130mg is stored in myoglobin.

Question 3

Name the two iron stores in the body.

Answer 3

Ferritin and Haemosiderin

Question 4

What is ferritin?

Answer 4

This is a soluble iron store which is found in the blood and can be measured with blood tests.

Question 5

What is the name of the condition when iron is deposited in many organs of the body?

Answer 5

Haemosiderosis.

Question 6

What is Haemosiderin?

Answer 6

This forms when there is either local or systemic iron excess and has a yellow/brown colour.

Question 7

How do our iron needs change throughout pregnancy?

Answer 7

When we pass 20 weeks gestation, our iron needs increase massively.

Question 8

What is the best source of iron from our diet? Haem or non-haem?

Answer 8

Haem iron is the best source of iron and we get it mainly from meat. Vegetarians rely a lot on non-haem iron.

Question 9

What must happen to non-haem iron before it can be transported across the intestinal epithelium?

Answer 9

The fe3+ ion must be converted to fe2+ before it can be absorbed.

Question 10

State the role of stomach acid in iron metabolism.

Answer 10

Stomach acid reduces fe3+ to fe2+ and it then binds to transferrin and is transported into the enterocytes.

Question 11

What is the fate of iron that has been absorbed?

Answer 11

It can be stored in enterocytes as transferrin or it is released into the blood stream and then stored in the liver or used for haemoglobin.

Question 12

What is ferroportin?

Answer 12

This transports iron out of cells.

Question 13

If taking iron supplements, which drinks are best to be taken with?

Answer 13

Vitamin C increases iron absorption. Tea and antacids neutralise the stomach acid and so reduce the potential absorption.

Question 14

What are erythroid cells?

Answer 14

These cells have many transferrin receptors and take up iron.

Question 15

How is iron from haemoglobin recycled?

Answer 15

When the erythrocyte nucleus is engulfed by the macrophages it is located in an erythroid cell island and so some is reused for the next generation of erythrocytes.

Question 16

What is hepcidin?

Answer 16

This is a negative regulator for iron absorption and degrades ferroportin.

Question 17

In what situations will the synthesis of hepcidin increase/decrease?

Answer 17

In iron overload its synthesis will increase and when there is high erythrocyte synthesis production will decrease.

Question 18

What form does the majority of iron stored in the liver found in? What is the rest?

Answer 18

95% of Iron stored in the liver is in the form of ferritin. The remainder is Haemosiderin found in kupffer cells.

Question 19

Name two causes of iron deficiency.

Answer 19

Poor absorption/ intake of iron. Increased use of iron e.g.physiologically pregnancy or pathologically bleeding.

Question 20

How will rbc present on a micrograph if there is iron deficiency?

Answer 20

There will be a larger area of pallor due to haemoglobin deficiency.

Question 21

State two major symptoms of iron deficiency.

Answer 21

Classic anaemia symptoms: pallor, tiredness

Epithelial changes: cracked lips and poor nails.

Question 22

What is the most commonly used measure of body iron?

Answer 22

Serum transferrin. This correlates with the amount of iron in body stores and so is generally the most accurate as it does not vary with eating.

Question 23

What can cause an increase in ferritin that’s not increased iron?

Answer 23

Acute and chronic inflammation, malignancy and liver disease.

Question 24

What does it tell us if a blood test returns wi decreased ferritin?

Answer 24

This indicates iron deficiency.

Question 25

What is the common supplement used for iron deficiency?

Answer 25

Ferrous sulphate.

Question 26

When is IM iron given?

Answer 26

Before surgery or during labour if iron levels need to be raised quickly.

Question 27

What is the problem with excess iron in the body?

Answer 27

If the capacity of transferrin to bind oxygen is exceeded then this leads to free iron in the blood. This is very dangerous as it can lead to free radical formation.

Question 28

What is haemochromatosis?

Answer 28

Haemochromatosis is where iron is deposited in the tissues and this leads to damage and pigmentation.

Question 29

What is hereditary haemochromatosis?

Answer 29

This is an autosomal recessive condition affecting how genes interact with hepcidin

Question 30

When can Haemosiderosis commonly occur?

Answer 30

After a blood transfusion.