Update on ferritin testing issue - private vs. NHS results

[KBird01]

Hi everyone. Posting as a new post, rather than add to the long thread on my previous post.

healthunlocked.com/pasoc/po...

I have a reply from Medichecks. Hmm... Whilst the info seems to align with what you posted   FlipperTD , they don't seem to have answered the questions I posed, or considered the info I provided. I see no explanation why their results are consistently almost double those of my NHS test results.

The new range is supposedly to align this with NICE guidelines [lower range of 30ug/l = iron deficiency]. It also appears the results dashboard 'tracker' is adjusted to accommodate the new range readings. My latest ferritin results are 89.2 ug/l [30-264], but on the tracker seem to be not far off the level of my first test, where in the same week I scored 24 with my NHS test. (19&22/3/19)

I asked them:

Medichecks results are consistently higher than NHS results, even when taken within a short time frame.

All tests were taken fasting, first thing on a morning.

No vitamin/iron supplements were taken for at least 3 days before a blood test.

The new Medichecks range is significantly different from the previous one. How do I now calculate results based on previous readings?

Here's an abridged version of their response:

'Lab reference ranges are determined internally and there can be significant differences in reference ranges between labs, especially when it comes to ferritin levels. In recognition of this issue, Medichecks performed an internal review of >25000 ferritin results over a 5 year period to determine our own reference ranges. We believe this is the largest ferritin reference range study to date. From this we have derived a new set of reference ranges that differ slightly depending on age and sex.'

'Regarding the laboratories that we use, our partner laboratories are fully accredited and are committed to the highest clinical standards by internal quality control (IQC) and external quality assurance...' [...etc]

'Next, regarding why Medichecks results may differ from those your doctor performed, there are several factors that affect blood test results which can be summarised as follows:

Biological variation (intra-individual variation)

In any individual, there are biological (diurnal) cycles that may affect blood results...' [Gives examples of how cortisol and testosterone levels vary through the day]

'With respect to ferritin in particular. Although this is a measure of iron stores it is also a marker which goes up if there is any level of infection or inflammation occurring within the body and hence we often see a variation in results as it does not solely reflect the iron stores.'

What they haven't done is explain why their results are consistently almost double my NHS results. My concern remains that as these consistently read above 30, I did not pick up the fact I had a long-standing ferritin deficiency as per NICE guidelines.

They then provide info and a link to this web page.

support.medichecks.com/hc/e...

I'm going to see if I can pick anyone's brains on the thyroid forum too, so I'll let you know what I find out...

Any other thoughts/info welcome in the meantime.🫤

[WIZARD6787]

My thoughts;

The issue for the difference in range is as you wrote different from the actual measurement difference. The range which is what is considered high or low is based on the laboratories assessment of all humans bodies and is different from laboratory to laboratory. No idea why there is no standardization other than the range is obviously not absolute although some proceed as if it were.

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You question of why Medichecks results are consistently higher than NHS results in your case was not answered. Instead information was given as to why blood tests results differ in general.

Guessing the author of the response is working from having absolute confidence that any approved laboratory will always without question have the same numerical result when testing any blood sample.

[KBird01 in reply to WIZARD6787]

Thanks WIZARD6787 . Yes, it's pretty frustrating that they don't seem inclined to answer this question. I understand that inflammation can raise ferritin, but my CRP levels have never been high. Other people on the Thyroid forum have had exactly the same experience.

I can see we're right back to FlipperTD's initial point that we can only see the NHS testing as correct really. As continual returns to my GP aren't an option I'm not really sure how to monitor my ferritin moving forward, other than to accept medichecks as being consistently inaccurate. 🤷‍♀️