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Flashcards in Iron Deck (21)
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1

Where does most iron reside in the body?

Ferrous (Fe2+) iron sits in porphyrin ring of Hb

2

What are the 3 compartments from which iron status is assessed?

Functional iron (bound to Hb)
Transport iron (bound to transferrin)
Stored iron (ferritin in liver)

3

How many binding sites are on transferrin for iron?

2

4

What does transferrin do?

Transport iron from donor tissue (macrophages, intestines, liver) to tissues (erythroid marrow)

5

What are holotransferrin and apotransferrin?

Holotransferrin: bound transferrin
Apotransferrin: unbound transferrin

6

Serum ferritin can also act as an acute phase protein. What is the implication of this?

Levels rise in infection, malignancy etc.

7

What are the intraluminal factors that affect iron absorption?

Solubility
Haem iron easier to absorb
Reduction of ferric iron to ferrous iron

8

What are the 2 main mucosal iron transporters that affect iron absorption?

DMT-1 on mucosal surface
Ferroportin on serosal surface

9

What is hepcidin and what effect does it have on iron absorption?

Produced in liver in response to iron overload
Down-regulates ferroportin to decrease iron absorption

10

Where in the body does iron absorption/pick-up occur?

Duodenum

11

What are the consequences of a negative iron balance?

Iron-deficient erythropoiesis
Decreasing MCV
Microcytic anaema
Epithelial changes (koilonychia, angular stomatitis)

12

List the main causes of iron deficiency

Dietary insufficiency
Bleeding
Malabsorption

13

How does iron overload (haemochromatosis) arise? What effect does it have on erythroid marrow?

Increased ferritin storage with decreased iron release (due to hepcidin), resulting in iron overload and impaired iron supply to erythroid marrow

14

List some clinical features of hereditary haemochromatosis

Weakness, fatigue
Joint pain
Impotence
Arthritis
Cirrhosis
Diabetes
Cardiomyopathy

15

Mutation in which gene accounts for 95% of hereditary haemochromatosis?

HFE gene encoding hepcidin

16

What are the diagnostic levels of serum ferritin for iron overload?

Over 300 micrograms/l in men
Over 200 micrograms/l in pre-menopausal women

17

When is a liver biopsy for haemochromatosis warranted?

If uncertain about iron overload
Assess tissue damage

18

How is hereditary haemochromatosis treated?

Weekly phlebotomy
Family screening

19

What is the typical cause of secondary iron overload?

Repeated blood transfusion

20

What is the treatment option for secondary iron overload?

Iron-chelating agents: desferrioxamine, deferiprone

21

How do iron-chelating agents work?

Bind iron to form complexes that are secreted in urine