What level of Serum Ferritin represents ’empty’? As in complete depletion of iron stores?
Is it any value below the minimum of the reference range? e.g. < 30 mcg/L
Or does the bottom of the reference range allow for a buffer and ’empty’ is substantially lower than this?
Could patients actually be ’empty’ but still have Serum Ferritin values within the normal range?
Could the same Serum Ferritin value occur in one patient on ’empty’ but with adequate stores in another?
The answers are: Maybe, Pretty much, Definitely yes and Absolutely!
Are you surprised? A little disappointed in this marker of iron status? You should be. Serum Ferritin, sold to us as being a reflection of our iron ‘stores’, at best demonstrates a poor correlation with actual hepatic iron content in most (and shows substantial inter-individual variability – so the same result can translate to substantially different amounts) and no correlation in many (inflammation, hepatocellular damage, excess adiposity). So…how well do you really know Ferritin and what healthy looks like?!
👑Prof. Rosalind Gibson of nutritional assessment, tells us that while controversy and confusion reign about what ’empty’ actually looks like, ‘overflowing’ is far more apparent & accurately spoken to by Serum Ferritin results and it occurs at levels within the standard reference range – that’s right – the cut-off for iron overload in women under 45yrs is just 150mcg/L!
Likewise, the best article ever written on Serum Ferritin (!!) – yep I am putting all my money on this one – by Kell & Pretorius published in the Royal Society of Chemistry Journal in 2014, eloquently explains why serum Ferritin is a bit of a fraud in terms of really reflecting the true iron story of any individual. Spoiler alert: its release into serum is not regulated but due to leakage from damaged cells and this version of ferritin found in serum is radically different in form and function from that found intracellularly anywhere! If Ferritin is starting to lose favour with you in terms of a preferred marker of iron status, you’re in good company.
My affections shifted a long time ago to Serum Transferrin and Transferrin Saturation % as my top 2 markers that tell the true tale of that individuals’ demand and supply status.
I certainly don’t disregard Serum Ferritin values. But I know what these do and don’t tell us about an individual’s iron status and more to the point I am clear about where I want & expect those to be for each sex and at any age. This is essential knowledge for all of us working in nutrition, because over-treatment with iron continues and it is driven by false goals and ideas about what ‘healthy looks like’, and ignores the Hyde side of iron’s well-established Jekyll & Hyde personality to our detriment.
UU30 So you think you know Ferritin?
Serum Ferritin has been sold to us as reflecting our patient’s iron stores and while we know there are some scenarios where this association is broken e.g. inflammation, how well does it reflect true hepatic iron content for the rest of us? Poorly, is the consensus. Why is this and what do Serum Ferritin results actually speak to then? Well, something quite different, it turns out – and generally as a consequence of this, more is not better! Given Ferritin is routinely reported on for patients with any iron concerns, what value can we still extract from these results then and are we getting closer to being able to describe what desirable results actually look like?
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Iron Package II
You can purchase UU30 Iron Package II here. If you are an Update in Under 30 Subscriber, you will find it waiting for you in your online account. You can become an Update in Under 30 Subscriber to access this episode and the entire library of Update in Under 30 audios and resources here.