Lecture 20 - Biochemical Assessment of Iron Status 1 Flashcards
what are some functions of iron
- oxygen carrying (haemoglobin)
- oxygen storage (myoglobin)
- oxidative production cellular energy
- glycolysis in muscles
- serotonin and norepinephrine production
- neutrophil function
consequences of iron deficiency anaemia
- decreased work capacity
- fatigue
- behavioural disturbances
- decreased cognitive function
- decreased growth
- spoon shaped nails
what are the consequences of non anaemic iron deficiency
- possibly decreased cognitive function
- possibly increased fatigue
- possibly decreased mood
- possibly decreased work capacity
- increased risk of iron deficiency anaemia
what is the aetiology of iron deficiency
- low intake or poor absorption
- high requirements : growth, blood loss, pregnancy
what groups are at risk of iron deficiency
- 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)
what is the relevance of clinical assessment of iron status
not used in research or monitoring setting but can be used if someone is in severe iron deficiency state
is dietary assessment used as assessment of iron status
yes
is anthropometric assessment used as assessment of iron status
not relavent
what is the most important nutritional assessment method in the assessment of iron status and why
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
red blood cells are broken down all the time by …..
reticulo-epithelial cells in areas like the liver and spleen
what happens when red blood cells are broken down
some is stored as ferratin other is used to make haemoglobin again
what are the 5 red cell indices when looking at iron status
- haemoglobin
- haematocrit (packed cell volume )
- mean cell volume
- red cell distribution width
- erythrocyte protoporphyrin
what is mean cell volume
Ht / RBC
relationship between haematocrit and red blood cell count
what is red cell distribution
the variation in the size of cells
what is erythrocyte protoporphyrin (FEP or ZIPP
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
what will happen to haemoglobin if you have iron deficiency anaemia
will decrease
what will happen to hematocrit if you have iron deficiency anaemia
decrease
what will happen to mean cell volume if you have iron deficiency anaemia
decrease
what will happen to red cell distribution width if you have iron deficiency anaemia
will be greater (some are small and some are normal so there will be a greater difference in size)
what will happen to eythrocyte protoporphyrin if you have iron deficiency anaemia
will be greater
what are the biochemical indices of iron status
- serum ferritin
- soluble transferrin receptor
- serum iron
- total iron binding capacity
- transferrin saturation
what is soluble transferrin receptor
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
why are we able to measure soluble transferrin receptor and ferratin in the blood
because some ferratin leaks out into the blood and some soluble transferrin receptor will bud off the cell into the blood
what is serum iron
how much is being transported on transferrin
what is total iron binding capacity
like the number of spots on transferrin that have not been taking up by iron, each can only carry two irons
what is transferrin saturation
serum Fe / TIBC
how saturated the transferrin is, how many of those sites are taken up with iron
ferratin is
how your body stores iron
what will happen to serum ferritin in iron deficiency
decrease
what will happen to soluble transferrin receptor in iron deficiency
increase
what will happen to serum Fe in iron deficiency
decrease
what will happen to total binding capacity in iron deficiency
increase (more binding sites are free)
what will happen to transferrin saturation in iron deficiency
decrease
what happens in stage 1 iron deficiency
body protects the red blood cell iron, but starting to get less in your iron stores
what happens to serum ferratin, transferrin saturation, erythrocyte protoporphyrin and haemoglobin in stage 1 iron deficiency
serum ferratin, = decrease
transferrin saturation, = normal
erythrocyte protoporphyrin = normal
haemoglobin = normal
what happens to serum ferratin, transferrin saturation, erythrocyte protoporphyrin and haemoglobin in stage 2 iron deficiency
serum ferratin, = decrease
transferrin saturation, = decrease
erythrocyte protoporphyrin = increase
haemoglobin = normal
what happens to serum ferratin, transferrin saturation, erythrocyte protoporphyrin and haemoglobin in stage 3 iron deficiency
serum ferratin, = decrease
transferrin saturation, = decrease
erythrocyte protoporphyrin = increase
haemoglobin = decrease
what happens in stage 2 iron deficiency
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
what happens in stage 3 iron deficiency
full iron deficiency anaemia, run out of stores, marked impact on your iron in red blood cells, haemoglobin dropped below the cut off
what do all three stages of iron deficiency represent
stage 1 = depleted iron stores
stage 2 = iron deficient erythropoiesis
stage 3 = iron deficiency anaemia
what are the three approaches to interpreting iron indices
- cut offs and reference limits
- multiparameter models
- body iron model
what is a cut off
when you are talking about impaired function, a level of this iron index below this cut off will have functional impacts
most commonly we have reference limits what are these
when you take a healthy population and look at the extremes of extremely low or high
multi parameter models …..
combine a whole lot of these indices together
reference limits are quite practical to use for
an individual in health or clinical setting
how do reference limits differ
by gender and age
what is a multi-parameter model for iron
ferritin model
using the ferritin model, someone will have iron deficient erythropoiesis (IDE) if
SF, TS, EP = 2+ are abnormal
Hb = normal
using the ferritin model someone will have iron deficiency anaemia (IDA) if
SF, TS, EP = 2+ are abnormal
Hb = low
what happens if someone has low haemoglobin but only 1 of SF, TS, EP are abnormal
anaemia due to something else
what is the body iron model
equation based on ratio of soluble transferrin receptor and serum ferritin
using the body iron model what is considered iron deficiency
body iron <0mg/kg
using the body iron model what is considered iron deficiency anaemia
iron deficiency and low Hb
what are the advantages to the body iron model
- good estimate of body iron measured by phlebotomy
- continuous variable
- less affected by inflammation
why is it good that the body iron model is a continuous variable
because then you can see if they are approaching a dangerous zone in terms of iron deficiency
why is the body iron model less affected by inflammation
because the soluble transferrin receptor isnt considered to be much affected by inflammation
what are the disadvantages of body iron model
- costs soluble transferrin receptor
- no standard method soluble transferrin receptor
prevalence of iron deficiency anaemia in 15-18 year olds NZ
5.2%
prevalence of iron deficiency in 15-18 year olds NZ
10.6%
