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HUNT242 > Lecture 20 > Flashcards

Lecture 20 Flashcards

Biochemical assessment of Iron status

1
Q

What are some functions of iron

A
  • oxygen carrying (haemoglobin)
  • oxygen storage (myoglobin)
  • oxidative production cellular energy
  • glycolysis in muscles
  • serotonin and norepinephrine production
  • neutrophil function
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2
Q

What are the consequences of iron deficiency anaemia

A
  • Decreased work capacity
  • fatigue
  • behavioural disturbances
  • decreased cognitive function
  • decreased growth
  • spoon shaped nails
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3
Q

what are the consequences of non anaemic iron deficiency

A
  • decreased cognitive function ?
  • increased fatigue ?
    -decreased mood ?
    -decreased work capacity
  • increased risk of iron deficiency anaemia
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4
Q

what is the aetiology of iron deficiency

A
  • Low intake or poor absorption
  • High requirements:
  • growth
  • Blood loss
  • pregnancy
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5
Q

what groups are at risk of iron deficiency

A
  • infants (especially pre term)
  • toddlers (~%30 suboptimal Fe status)
  • people who are menstruating (~13%)
  • pregnant people
  • blood loss
  • vegetarians (increased phytate intake, no intake red meat or meat, fish, poultry factor)
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6
Q

what is the relevance of clinical assessment of iron status

A

Not used in research or monitoring setting but can be used if someone is in severe iron deficiency state

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7
Q

What is dietary assessment used as

A

For sure looks at risk of looking at risk of iron deficiency
- Where some areas of weaknesses
- Can not tell you if you are deficient or not
- Overall indicator of how many people are at risk in a population

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8
Q

Is anthropometric assessment used as assessment of iron status

A

not relavent

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9
Q

Biochemical assessment is …

A

This is really important because the amount of iron you absorb is based on your status, enhancers and inhibitors
- This can tell you if you are deficient

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10
Q

Iron metabolism and red blood cell recycling.
step 1:

A

Dietary iron comes into the body and some of it is being absorbed by epithelial cells in the intestine

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11
Q

Iron metabolism and red blood cell recycling.
step 2:

A

What isn’t absorbed is going to end up going out in faeces

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12
Q

Iron metabolism and red blood cell recycling.
step 3:

A

What is absorbed is going to end up going into the body, transported on transferrin (Fe3+)

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13
Q

Iron metabolism and red blood cell recycling.
step 4:

A

Will eventually end up going to a site of erythropoiesis, and that mainly happens in the bone marrow
Erythro =means red cell

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14
Q

Iron metabolism and red blood cell recycling.
step 5:

A

We have the formation of red blood cell. There are a number of things you can measure when looking at iron status. Could look at haemoglobin concentration, and a number of other indices
Iron is an important component of Haemoglobin molecule, which enables oxygen to be carried in the blood.

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15
Q

Iron metabolism and red blood cell recycling.
step 6:

A

The haemoglobin is always being recycled. We have relatively small intake of iron compared to the amount of iron needed to replace your red blood cells every approx. 120 days.

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16
Q

Iron metabolism and red blood cell recycling.
step 7:

A

These red blood cells are being broken down all the time by RE cells, which are mainly in areas like the liver and the spleen. When they are broken down, that which is not needed is stored as ferritin which can end up in the blood etc. Others will be reused to make new Haemoglobin (the recycling)

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17
Q

What are the 5 red cell indices when looking at iron status

A
  • haemoglobin
  • haematocrit (packed cell volume )
  • mean cell volume
  • red cell distribution width
  • erythrocyte protoporphyrin
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18
Q

What is mean cell volume

A

Ht / RBC

Relationship between haematocrit and red blood cell count

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19
Q

what is red cell distribution

A

the variation in the size of cells

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20
Q

what is erythrocyte protoporphyrin (FEP or ZPP)

A

the immature stage in the production of haemoglobin

zinc will be replaced by iron in this process but if you don’t have enough iron then the zinc stays and you have erythrocyte protoporphyrin instead of heme

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21
Q

what will happen to haemoglobin if you have iron deficiency anaemia

A

decrease

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22
Q

what will happen to hematocrit if you have iron deficiency anaemia

A

decrease

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23
Q

what will happen to mean cell volume if you have iron deficiency anaemia

A

decrease

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24
Q

what will happen to red cell distribution width if you have iron deficiency anaemia

A

will be greater (some are small and some are normal so there will be a greater difference in size)

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25
Q

what will happen to eythrocyte protoporphyrin if you have iron deficiency anaemia

A

will be greater

26
Q

what are the biochemical indices of iron status

A
  • serum ferritin
  • soluble transferrin receptor
  • serum iron
  • total iron binding capacity
  • transferrin saturation
27
Q

Serum iron

A

How much iron is being transported in the transferrin

28
Q

Total iron binding compacity

A

number of spots that haven’t been taken ip from the iron

29
Q

Transferrin saturation

A

how many of these sites are occupied by the iron

30
Q

Ferritin is what

A

the Iron is stored as until the Iron is needed

31
Q

what is soluble transferrin receptor

A

the receptor for picking up the transferrin

the hungrier that a cell is for iron, the more receptors it will put on the surface to pick up more iron

32
Q

why are we able to measure soluble transferrin receptor and ferratin in the blood

A

because some ferritin leaks out into the blood and some soluble transferrin receptor will bud off the cell into the blood

33
Q

How many irons can the transferrin hold

A

Two irons

34
Q

what will happen to serum ferritin in iron deficiency

A

decrease

35
Q

what will happen to soluble transferrin receptor in iron deficiency

A

increase

36
Q

what will happen to serum Fe in iron deficiency

A

decrease

37
Q

what will happen to total binding capacity in iron deficiency

A

increase (more binding sites are free)

38
Q

what is transferrin saturation

A

serum Fe / TIBC

how saturated the iron is, how many of those sites are taken up with iron

39
Q

what will happen to transferrin saturation in iron deficiency

A

decrease

40
Q

what happens in stage 1 iron deficiency

A

Depletion iron stores

41
Q

what happens to serum ferratin, transferrin saturation, erythrocyte protoporphyrin and haemoglobin in stage 1 iron deficiency

A

serum ferratin, = decrease

transferrin saturation, = normal

erythrocyte protoporphyrin = normal

haemoglobin = normal

42
Q

Stage 2 of iron deficiency

A

Iron deficient erythropoiesis

basically just about run out of iron stores starting to have slight impact on red blood cell iron but not to the point where your hemoglobin would be below the cut off

43
Q

what happens to serum ferratin, transferrin saturation, erythrocyte protoporphyrin and haemoglobin in stage 2 iron deficiency

A

serum ferratin, = decrease

transferrin saturation, = decrease

erythrocyte protoporphyrin = increase

haemoglobin = normal

44
Q

Stage 3 of iron deficiency

A

Iron deficiency anaemia

run out of stores, marked impact on your iron in red blood cells, haemoglobin dropped below the cut off

45
Q

what happens to serum ferratin, transferrin saturation, erythrocyte protoporphyrin and haemoglobin in stage 3 iron deficiency

A

serum ferratin, = decrease

transferrin saturation, = decrease

erythrocyte protoporphyrin = increase

haemoglobin = decrease

46
Q

what are the three approaches to interpreting iron indices

A
  1. cut offs and reference limits
  2. multiparameter models
  3. body iron model
47
Q

What is a cut off

A

when you are talking about impaired function, a level of this iron index below this cut off will have functional impacts

48
Q

most commonly we have reference limits what are these

A

when you take a healthy population and look at the extremes of extremely low or high

49
Q

multi parameter models …..

A

combine a whole lot of these indices together

50
Q

how do reference limits differ

A

by gender and age

51
Q

what is a multi-parameter model for iron

A

ferritin model

52
Q

using the ferritin model, someone will have iron deficient erythropoiesis (IDE) if

A

SF, TS, EP = 2+ are abnormal

Hb = normal

53
Q

using the ferritin model someone will have iron deficiency anaemia (IDA) if

A

SF, TS, EP = 2+ are abnormal

Hb = low

54
Q

what happens if someone has low haemoglobin but only 1 of SF, TS, EP are abnormal

A

anaemia due to something else

55
Q

what is the body iron model

A

equation based on ratio of soluble transferrin receptor and serum ferritin

56
Q

using the body iron model what is considered iron deficiency

A

body iron <0mg/kg

57
Q

using the body iron model what is considered iron deficiency anaemia

A

iron deficiency and low Hb

58
Q

what are the advantages to the body iron model

A
  • good estimate of body iron measured by phlebotomy
  • continuous variable
  • less affected by inflammation
59
Q

why is it good that the body iron model is a continuous variable

A

because then you can see if they are approaching a dangerous zone in terms of iron deficiency

60
Q

why is the body iron model less affected by inflammation

A

because the soluble transferrin receptor isnt considered to be much affected by inflammation

61
Q

what are the disadvantages of body iron model

A
  • costs soluble transferrin receptor
  • no standard method soluble transferrin receptor

HUNT242 (23 decks)

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