Iron

Question 1

The majority of iron is found in what state?

Answer 1

Haemoglobin

Question 2

Where does iron absorption take place?

Answer 2

Duodenum

Question 3

Give factors that enhance iron absorption

Answer 3

Acidic environment

Alcohol

Question 4

Give factors that inhibit iron absorption

Answer 4

Tannins
Phytates
Calcium

Question 5

What enzyme is responsible for reducing ferric iron to ferrous?

Answer 5

Duodenal cytochrome B

Question 6

What is the importance of duodenal cytochrome B?

Answer 6

As iron is only able to be transported in the ferrous state

Question 7

What transporter transports ferrous into the duodenal enterocyte?

Answer 7

DMT-1

Question 8

What is the role of ferroportin?

Answer 8

To facilitate iron export from the enterocyte to transferrin

Question 9

What protein is the main negative regulator of iron absorption?

Answer 9

Hepcidin

Question 10

How does hepcidin work?

Answer 10

It binds to ferroportin and degrades it preventing iron export to transferrin

Question 11

Give two causes of hepcidin production

Answer 11

Increased iron load

Inflammation

Question 12

What is used to measure functional iron levels?

Answer 12

Haemoglobin concentration

Question 13

What is used to assess transport iron levels?

Answer 13

% saturation of transferrin with iron

Question 14

What is used to assess storage iron levels?

Answer 14

Serum ferritin

Question 15

In cases of iron overload will transferrin saturation be increased or decreased?

Answer 15

Increased

Question 16

Why is it significant that ferritin is an acute phase protein?

Answer 16

As it will go up with infection, malignancy etc. and so may be raised even if iron is not

Question 17

Give some causes of iron deficiency

Answer 17

Insufficient intake
Bleeding
Malabsorption

Question 18

Outline the pathophysiology of anaemia of chronic disease

Answer 18

Inflammatory cytokines stimulate ferritin synthesis and cause hepcidin to block ferroportin

Question 19

What is the effect of increased hepcidin in AOCD?

Answer 19

There is impaired iron supply to marrow erythroblasts and hypochromic red cells

Question 20

What is the main cause of primary iron overload?

Answer 20

Hereditary haemochromatosis

Question 21

The main form of hereditary haemochromatosis is due to mutations in which gene?

Answer 21

HFE

Question 22

What is the effect of HFE mutations?

Answer 22

Decreased synthesis of hepcidin causing increased iron absorption

Question 23

In haemochromatosis, a massive amount of iron is accumulated over a short period of time. True/false?

Answer 23

False - gradual accumulation over years that can lead to end-organ damage

Question 24

Give some clinical features of haemochromatosis

Answer 24

Weakness
Joint pains
Cirrhosis
Impotence
Diabetes
Cardiomyopathy

Question 25

What homozygous mutation in the HFE gene can result in hereditary haemochromatosis?

Answer 25

C282Y

Question 26

What transferrin saturation suggests haemochromatosis?

Answer 26

>50%

Question 27

What serum ferritin levels suggests haemochromatosis?

Answer 27

>300 in men | >200 in pre-menopausal women

Question 28

How is hereditary haemochromatosis treated?

Answer 28

Weekly venesection

Question 29

What are the aims of venesection treatment in haemochromatosis?

Answer 29

Exhaust iron stores so ferritin around 20 | Thereafter keep ferritin <50

Question 30

What is the main cause of secondary iron-loading anaemia?

Answer 30

Repeated red cell transfusions

Question 31

How is secondary iron overload treated?

Answer 31

Iron chelating agents (desferrioxamine)