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haematology > Iron health and disease > Flashcards

Iron health and disease Flashcards

1
Q

functions of iron

A

oxygen transport in Hb

electron transport in mitochondria

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2
Q

Iron is a safe element, true or false

A

FALSE

it is dangerous

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3
Q

why is iron dangerous and what needs to be done as a result

A

due to production of free radicals and oxidative stress

iron needs to be transported and stored safely

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4
Q

how is iron excreted

A

it is not

there is no mechanism for this

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5
Q

where is the majority of iron found in the body

A

in Hb (haem)

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6
Q

why do macrophages have an iron store

A

because they take up aged RBCs which contain iron

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7
Q

how can iron loss occur

A

physiological bleeding

shedding of skin cells, enterocytes

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8
Q

where does iron absorption occur

A

duodenum - proximal gut

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9
Q

which dietary factors increase iron absorption

A

haem iron transporter - haem iron
ascorbic acid
alcohol

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10
Q

which absorbs easier, haem or non-haem iron

A

haem iron due to presence of haem iron transporter

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11
Q

which dietary factors decrease iron absorption

A

tannins in tea
phytates - nuts, cereal, seeds
calcium

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12
Q

Where is Duodenal Cytochrome B enzyme found

What is its function

A

luminal surface of gut wall

reduces Fe3+ to Fe2+

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13
Q

what is the function of DMT-1

A

transports Fe2+ into duodenal enterocyte

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14
Q

what is the function of ferroportin

A

exports iron out of the enterocyte and passes it onto transferrin

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15
Q

what is hepcidin

A

major negative feedback regulator of iron absorption

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16
Q

where is hepcidin produced

A

in the liver in response to ^ iron or inflammation

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17
Q

how does hepcidin work

A

binds to ferroportin and degrades it meaning iron is trapped in duodenal enterocytes and macrophages
It cannot get to the rest of the body

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18
Q

Hepcidin levels are high/low in iron deficiency

A

low

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19
Q

in order to bind to transferrin, iron must be oxidised/reduced

A

oxidised - in the Fe3+ state

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20
Q

How can you assess iron status

A

functional iron
transported iron
storage iron

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21
Q

how do you measure functional iron

A

Hb concentration

22
Q

how do you measure transported iron

A

% saturation of transferrin with iron

23
Q

how do you measure storage iron

A

serum ferritin

24
Q

what is transferrin

A

protein containing 2 binding sites for iron

to make Fe3+ safer

25
Q

what is the role of transferrin

A

transports Fe3+ from donor tissue (macrophages, liver, intestines) to cells expressing transferrin receptor eg erythroid marrow

26
Q

what do cells expressing transferrin receptors do

A

internalise transferrin/Fe3+ complex, use iron and release transferrin back out

27
Q

holotransferrin has bound/unbound iron

A

bound iron

28
Q

what is the normal % transferrin saturation

A

20-50%

29
Q

in iron overload, what is % transferrin saturation like

A

elevated

30
Q

in iron deficiency, what is % transferrin saturation like

A

reduced

31
Q

What is ferritin

A

intracellular spherical protein that stores Fe3+

32
Q

what is serum ferritin a marker of

A

indirect marker of storage iron

33
Q

serum ferritin is also an acute phase protein, true or false

A

TRUE

34
Q

what is a cause of low ferritin

A

iron deficiency

35
Q

what are causes of high ferritin

A

iron overload
infection
malignancy
inflammation

36
Q

What are disorders of iron metabolism

A

iron deficiency
iron malutilisation
iron overload

37
Q

how is iron deficiency confirmed

A

low Hb

low ferritin

38
Q

what is the most important thing to do in iron deficiency anaemia

A

identify a cause

39
Q

what is a cause of iron malutilisation

A

anaemia of chronic disease

40
Q

what is the pathophysiology of anaemia of chronic disease

A

upregulated ferritin levels therefore increase in storage iron even though normal iron is the same
hepcidin levels increase which destroy ferroportin and so iron is unable to leave the cells to get to the rest of the body

41
Q

what are the findings in anaemia of chronic disease

A

high ferritin

low % transferrin saturation

42
Q

what are the categories of iron overload

A

primary

secondary

43
Q

define iron overload

A

> 5g

44
Q

example of primary iron overload

A

hereditary haemochromatosis

AR

45
Q

pathophysiology of haemochromatosis

A

mutation in HFE gene which decreases hepcidin levels

this means there is more iron absorption over a gradual period of time which can result in end organ damage

46
Q

what tests are done for haemochromatosis

A

genetics
transferrin saturation - high
ferritin - high

47
Q

symptoms of haemochromatosis

A 
arthralgia 
fatigue
cardiomyopathy 
liver disease 
DM
48
Q

management of haemochromatosis

A

weekly venesection to exhaust ferritin stores <20

then keep levels under 50

49
Q

why is haemochromatosis problematic

A

because you can be asymptomatic and disease is irreversible

50
Q

what are secondary causes of iron overload

A

repeated red cell transfusions
thalassaemias
sideroblastic anaemia
refracory hypoplastic anaemia

51
Q

management of secondary iron overload

A

iron chelating drugs

haematology (26 decks)

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