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Haematology Year 3 > Iron > Flashcards

Iron Flashcards

1
Q

what is iron essential for

A

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

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2
Q

what mitochondrial process is iron needed for

A

ATP production

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3
Q

what can chemical reactivity with iron cause

A

oxidative stress

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4
Q

why is iron difficult to get rid of in the body

A

there is no mechanism for excretion

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5
Q

where is the major of the body iron found

A

haem (2500mg)

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6
Q

where does iron sit in haem

A

porphyrin ring

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7
Q

where else is iron stored in the body

A 
macrophage stores (500mg)
liver stores (500mg)
erythroid marrow (150mg)
plasma (4mg)
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8
Q

what is the only way to influence iron levels

A

through absorption

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9
Q

where is iron absorbed

A

duodenum

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10
Q

what transports iron into duodenal enterocyte

A

DMT

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11
Q

what facilitates iron export from duodenal enterocyte

A

ferroportin

passes it on to transferrin

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12
Q

what transports iron around the body

A

transferrin

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13
Q

what down regulates ferroportin to decrease iron uptake

A

hepcidin

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14
Q

where is hepcidin produced

A

liver in response to iron load and inflammation

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15
Q

how can iron status be assessed

A
  1. function iron: Hb concentration
  2. transport iron/iron supply to tissue: % transferrin saturation with iron
  3. storage iron: serum ferritin/tissue biopsy
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16
Q

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

A

bone marrow

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17
Q

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

A

liver

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18
Q

role of transferrin

A

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

19
Q

how many binding sites for iron does transferrin have

A

2

20
Q

what form of iron does transferrin bind to

A

Fe3+

21
Q

what does transferrin saturation measure

A

iron supply

22
Q

what is holotransferrin

A

transferrin bound to iron

23
Q

what is apotransferrin

A

unbound transferrin

24
Q

how is transferrin affected in iron overload

A

the transferrin saturation is increased

25
Q

what is ferritin

A

large protein, stores iron in Fe 3+ form

26
Q

what do serum ferritin levels show

A

indirect measure of iron storage

27
Q

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

A

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

28
Q

when would serum ferritin levels be low

A

iron deficiency

29
Q

consequences of a negative iron balance

A
  1. exhaustion of iron stores
  2. iron deficient erythropoiesis – falling MCV
  3. Microcytic anaemia
  4. epithelial changes - koilonychia, angular stomatitis
30
Q

disorders of iron metabolism

A

iron deficiency
iron overload
iron malutilisation- anaemia of chronic disease

31
Q

causes of microcytic hypochromic anaemia

A

iron deficiency

globin deficiency
- thalassaemia

32
Q

difference between iron deficiency anaemia and anaemia of chronic disease

A

ferritin is low in iron deficiency

33
Q

causes of iron deficiency

A

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

34
Q

causes of chronic blood loss that can result in iron deficiency

A

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

35
Q

maximun daily absorption of iron

A

4-5mg

36
Q

what happens in anaemia of chronic disease

A
  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
37
Q

what is primary iron overload

A

long term excess iron absorption

parenchymal iron loading – organ damage

38
Q

what is hereditary haemochromatosis

A

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

39
Q

features of hereditary haemochromatosis

A 
weakness
fatigue 
joint pains
impotence
arthritis 
cirrhosis 
diabetes 
cardiomyopathy
bronze skin
40
Q

blood results in haemochromatosis

A

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

41
Q

treatment of hereditary haemochromatosis

A

weekly venesection (blood removal)

  • 450-500ml
  • initial aim to exhaust iron stores
  • keep ferritin under 50
42
Q

what causes iron loading anaemia

A

repeated red cell transfusions

excessive iron absorption related to over-active erythropoiesis

43
Q

conditions and their treatments that may cause iron loading anaemia

A

thalassaemia
sideroblastic anaemia
red cell aplasia
myelodysplasia

44
Q

treatment of patients with iron loading anaemia

A

NOT VENESECTION: already anaemic so do not want to remove blood

iron chelating agents: desferrioxamine (SC/IV)

Haematology Year 3 (21 decks)

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