Iron

Question 1

what is iron essential for

Answer 1

oxygen transport
electron transport
present in: Hb, myoglobin, enzymes

Question 2

what mitochondrial process is iron needed for

Answer 2

ATP production

Question 3

what can chemical reactivity with iron cause

Answer 3

oxidative stress

Question 4

why is iron difficult to get rid of in the body

Answer 4

there is no mechanism for excretion

Question 5

where is the major of the body iron found

Answer 5

haem (2500mg)

Question 6

where does iron sit in haem

Answer 6

porphyrin ring

Question 7

where else is iron stored in the body

Answer 7

macrophage stores (500mg)
liver stores (500mg)
erythroid marrow (150mg)
plasma (4mg)

Question 8

what is the only way to influence iron levels

Answer 8

through absorption

Question 9

where is iron absorbed

Answer 9

duodenum

Question 10

what transports iron into duodenal enterocyte

Answer 10

DMT

Question 11

what facilitates iron export from duodenal enterocyte

Answer 11

ferroportin

passes it on to transferrin

Question 12

what transports iron around the body

Answer 12

transferrin

Question 13

what down regulates ferroportin to decrease iron uptake

Answer 13

hepcidin

Question 14

where is hepcidin produced

Answer 14

liver in response to iron load and inflammation

Question 15

how can iron status be assessed

Answer 15

1. function iron: Hb concentration
2. transport iron/iron supply to tissue: % transferrin saturation with iron
3. storage iron: serum ferritin/tissue biopsy

Question 16

where do you take a tissue biopsy to look for iron deficiency

Answer 16

bone marrow

Question 17

where do you take a tissue biopsy to look for iron overload

Answer 17

liver

Question 18

role of transferrin

Answer 18

transports iron from donor tissues (macrophage/intestinal cells and hepatocytes) to tissues expressing transferrin receptors
i.e. tissues that need it

Question 19

how many binding sites for iron does transferrin have

Answer 19

2

Question 20

what form of iron does transferrin bind to

Answer 20

Fe3+

Question 21

what does transferrin saturation measure

Answer 21

iron supply

Question 22

what is holotransferrin

Answer 22

transferrin bound to iron

Question 23

what is apotransferrin

Answer 23

unbound transferrin

Question 24

how is transferrin affected in iron overload

Answer 24

the transferrin saturation is increased

Question 25

what is ferritin

Answer 25

large protein, stores iron in Fe 3+ form

Question 26

what do serum ferritin levels show

Answer 26

indirect measure of iron storage

Question 27

why does an increase in ferritin level not necessarily have anything to do with iron

Answer 27

acts as an acute phase protein and will be increased with infection, malignancy ect

Question 28

when would serum ferritin levels be low

Answer 28

iron deficiency

Question 29

consequences of a negative iron balance

Answer 29

1. exhaustion of iron stores 2. iron deficient erythropoiesis -- falling MCV 3. Microcytic anaemia 4. epithelial changes - koilonychia, angular stomatitis

Question 30

disorders of iron metabolism

Answer 30

iron deficiency iron overload iron malutilisation- anaemia of chronic disease

Question 31

causes of microcytic hypochromic anaemia

Answer 31

iron deficiency globin deficiency - thalassaemia

Question 32

difference between iron deficiency anaemia and anaemia of chronic disease

Answer 32

ferritin is low in iron deficiency

Question 33

causes of iron deficiency

Answer 33

insufficient intake- dietary factors losing too much- bleeding not absorbing enough- malabsorption

Question 34

causes of chronic blood loss that can result in iron deficiency

Answer 34

menorrhagia GI- tumours, ulcers, NSAIDs, parasitic infection Haematuria

Question 35

maximun daily absorption of iron

Answer 35

4-5mg

Question 36

what happens in anaemia of chronic disease

Answer 36

1. increased transcription of ferritin mRNA stimulated by inflammatory cytokines (ferritin synthesis increased) 2. increased plasma hepcidin blocks ferroportin - mediated release of iron 3. results in impaired iron supply to marrow erythroblasts and eventually hypo chromic red cells

Question 37

what is primary iron overload

Answer 37

long term excess iron absorption | parenchymal iron loading -- organ damage

Question 38

what is hereditary haemochromatosis

Answer 38

mutations in HFE gene on chromosome 6 decreased hepcidin synthesis -- increased iron absorption presents around middle age

Question 39

features of hereditary haemochromatosis

Answer 39

``` weakness fatigue joint pains impotence arthritis cirrhosis diabetes cardiomyopathy bronze skin ```

Question 40

blood results in haemochromatosis

Answer 40

increased LFT's increased serum ferritin transferrin saturation >50% (high)

Question 41

treatment of hereditary haemochromatosis

Answer 41

weekly venesection (blood removal) - 450-500ml - initial aim to exhaust iron stores - keep ferritin under 50

Question 42

what causes iron loading anaemia

Answer 42

repeated red cell transfusions | excessive iron absorption related to over-active erythropoiesis

Question 43

conditions and their treatments that may cause iron loading anaemia

Answer 43

thalassaemia sideroblastic anaemia red cell aplasia myelodysplasia

Question 44

treatment of patients with iron loading anaemia

Answer 44

NOT VENESECTION: already anaemic so do not want to remove blood iron chelating agents: desferrioxamine (SC/IV)