Lecture 20 - Biochemical Assessment of Iron Status 1 Flashcards

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

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
  • possibly decreased cognitive function
  • possibly increased fatigue
  • possibly decreased mood
  • possibly 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

is dietary assessment used as assessment of iron status

A

yes

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8
Q

is anthropometric assessment used as assessment of iron status

A

not relavent

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9
Q

what is the most important nutritional assessment method in the assessment of iron status and why

A

biochemical assessment

  • the amount you absorb is massively affected by what your iron stores are and by enhances + inhibitors
  • you can not tell whether someone is iron deficient from dietary assessment, you must use biochemical assessment
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10
Q

red blood cells are broken down all the time by …..

A

reticulo-epithelial cells in areas like the liver and spleen

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11
Q

what happens when red blood cells are broken down

A

some is stored as ferratin other is used to make haemoglobin again

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12
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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13
Q

what is mean cell volume

A

Ht / RBC

relationship between haematocrit and red blood cell count

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14
Q

what is red cell distribution

A

the variation in the size of cells

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15
Q

what is erythrocyte protoporphyrin (FEP or ZIPP

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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16
Q

what will happen to haemoglobin if you have iron deficiency anaemia

A

will decrease

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17
Q

what will happen to hematocrit if you have iron deficiency anaemia

A

decrease

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18
Q

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

A

decrease

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19
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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20
Q

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

A

will be greater

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21
Q

what are the biochemical indices of iron status

A
  • serum ferritin
  • soluble transferrin receptor
  • serum iron
  • total iron binding capacity
  • transferrin saturation
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22
Q

what is soluble transferrin receptor

A

the receptor for pricking 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

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23
Q

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

A

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

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24
Q

what is serum iron

A

how much is being transported on transferrin

25
Q

what is total iron binding capacity

A

like the number of spots on transferrin that have not been taking up by iron, each can only carry two irons

26
Q

what is transferrin saturation

A

serum Fe / TIBC

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

27
Q

ferratin is

A

how your body stores iron

28
Q

what will happen to serum ferritin in iron deficiency

A

decrease

29
Q

what will happen to soluble transferrin receptor in iron deficiency

A

increase

30
Q

what will happen to serum Fe in iron deficiency

A

decrease

31
Q

what will happen to total binding capacity in iron deficiency

A

increase (more binding sites are free)

32
Q

what will happen to transferrin saturation in iron deficiency

A

decrease

33
Q

what happens in stage 1 iron deficiency

A

body protects the red blood cell iron, but starting to get less in your iron stores

34
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

35
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

36
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

37
Q

what happens in stage 2 iron deficiency

A

iron deficiency erythropoisis (IDE), 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

38
Q

what happens in stage 3 iron deficiency

A

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

39
Q

what do all three stages of iron deficiency represent

A

stage 1 = depleted iron stores

stage 2 = iron deficient erythropoiesis

stage 3 = iron deficiency anaemia

40
Q

what are the three approaches to interpreting iron indices

A
  1. cut offs and reference limits
  2. multiparameter models
  3. body iron model
41
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

42
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

43
Q

multi parameter models …..

A

combine a whole lot of these indices together

44
Q

reference limits are quite practical to use for

A

an individual in health or clinical setting

45
Q

how do reference limits differ

A

by gender and age

46
Q

what is a multi-parameter model for iron

A

ferritin model

47
Q

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

A

SF, TS, EP = 2+ are abnormal

Hb = normal

48
Q

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

A

SF, TS, EP = 2+ are abnormal

Hb = low

49
Q

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

A

anaemia due to something else

50
Q

what is the body iron model

A

equation based on ratio of soluble transferrin receptor and serum ferritin

51
Q

using the body iron model what is considered iron deficiency

A

body iron <0mg/kg

52
Q

using the body iron model what is considered iron deficiency anaemia

A

iron deficiency and low Hb

53
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
54
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

55
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

56
Q

what are the disadvantages of body iron model

A
  • costs soluble transferrin receptor
  • no standard method soluble transferrin receptor
57
Q

prevalence of iron deficiency anaemia in 15-18 year olds NZ

A

5.2%

58
Q

prevalence of iron deficiency in 15-18 year olds NZ

A

10.6%