Iron

Question 1

Where is the majority of iron in the body found ?

Answer 1

In haem

Question 2

Describe iron absorption in the duodenum?

Answer 2

DMT-1 transports iron into duodenal enterocyte
Ferroportin facilitates iron export from enterocyte and passes on to transferrin for transport elsewhere
Hepcidin down regulates ferroportin

Question 3

Assessing functional iron?

Answer 3

Hb conc

Question 4

Assessing transported iron?

Answer 4

%saturation of transferrin

Question 5

Assessing iron storage?

Answer 5

Serum ferritin

Tissue biopsy

Question 6

What is transferrin?

Answer 6

A protein

Transports iron from donor tissues to tissues with transferrin receptors

Question 7

How do you calculate transferrin saturation?

Answer 7

(Serum iron/ total iron binding capacity) *100

Question 8

What is halotransferrin?

Answer 8

Iron bound to transferrin

Question 9

What is apotransferrin?

Answer 9

Unbound transferrin

Question 10

What is normal transferrin saturation?

Answer 10

About 20-50%

Question 11

What causes serum ferritin to increase?

Answer 11

Infection

Malignancy

Question 12

List some disorders of iron metabolism

Answer 12

Iron deficiency
Iron malutilisation
Iron overload

Question 13

Describe the process of anaemia of chronic disease

Answer 13

Increased transcription of ferritin mRNA stimulated by inflammatory cytokines -> increased ferritin synthesis
Increased plasma hepcidin blocks ferroportin mediated release of iron
Results in impaired iron supply to marrow erythroblasts

Question 14

Primary cause of iron overload ?

Answer 14

Hereditary haemachromatosis

Question 15

Secondary causes of iron overload?

Answer 15

Transfusional

Iron loading anaemias

Question 16

What happens in hereditary haemachromatosis to cause iron overload?

Answer 16

Decreases synthesis of hepcidin
Increased iron absorption
Gradual iron accumulation

Question 17

When does hereditary haemachromatosis generally present?

Answer 17

Middle aged

Question 18

Clinical features of hereditary haemochromatosis?

Answer 18

Weakness / fatigue
Joint pains
Impotence

Question 19

Potential end organ damage in hereditary haemachromatosis ?

Answer 19

Cirrhosis
Diabetes
Cardiomyopathy
Arthritis

Question 20

Treatment of hereditary haemachromatosis?

Answer 20

Weekly venesection

Initially want to exhaust iron stores (ferritin <20) and then keep them under control (ferritin <50)

Question 21

Treatment of secondary iron overload?

Answer 21

Iron chelating agents - desferrioxamine

Question 22

Sources of iron overload in iron loading anaemias

Answer 22

Repeated red cell transfusions

Excessive iron absorption related to over active erythopoiesis