hi all
I've posted about this many times before (link included below) but in summary I am in conversation with medichecks because I've had several blood tests with medichecks and the NHS, with (to me) large variations. Culminating in the final blood draw being on the same day, all taken at same time, by same NHS nurse. One test went off to the NHS, one went off to the Doctors laboratory (TDL) and one went to County Labs... the latter both medichecks. These came back with three different results - the highest at 53 ug/L (county) and lowest at 27 ug/L (NHS). (results in pic)
I now have a reply from the medichecks doctor who has discussed these results with a colleague at another university, and in conclusion they say this is an acceptable and normal variation. This "acceptable and normal" variation is a fluctuation of 23 ug/L - i.e. NHS often a bit "low" and medichecks often a bit "high". I guess if nothing else, you can read your own overlay onto whichever results you get.
They recommend sticking with one provider for your results to avoid that variation - but my concern is that this would be fine if my 'county lab' results followed the same trend of slightly increasing results over 2020 but they go up and down.
To add to this, from the previous discussion, the longer your blood draw is in transit, the more it degrades, leading to a higher concentration of ferritin and therefore a higher result.
For this reason I think i shall be asking medichecks to only send my results to TDL going forwards- and discounting results by a percentage if they take a little longer to get there.
Reply from medichecks:
I have discussed your results with the chair of our clinical governance committee, who is also a Consultant Chemical Pathologist at Nottingham University Hospital.
We have jointly looked at the external quality assurance data for the Beckmann Access analysers used by your NHS lab, and the Roche analysers used by both TDL and County Pathology in their work for Medichecks. As we have discussed previously the EQA scheme involves sending identical samples to labs around the country and asking them to perform a ferritin measurement using their analysers. Based upon this we were both in agreement that the variability seen between your various results was within the amount expected when comparing between laboratories.
In the latest round of results labs which were using Beckman Access analysers returned lower results than those which were using Roche. The Beckman analysers returned a result which was on average 23% lower than the average for all laboratories, and the Roche analysers returned a result which was on average 17% higher than the average for all laboratories. This fits with the difference that we see in your results, where your NHS results have generally returned lower levels than those you have received through Medichecks. When we look at the degree of variability seen between the 353 laboratory analysers which are assessed as part of this scheme a sample which has an average result of 123 ug/L has a standard deviation of 23ug/L. This means that ferritin levels are quite variable when compared between laboratories which are using different platforms. Whilst there is less variability when comparing between laboratories which are both using the same platform, the variability seen between your results from County and TDL is within the amount that is considered normal when compared to the external quality assurance data.
In summary ferritin is one of the results which varies quite widely when we try to compare results between laboratories, and so it is important to be consistent and rely on results from one laboratory when you are tracking results over time.
What do you all think? I haven't replied yet as, as always, keen to get your perspective on things.
Link to previous post on this (which links back to all the previous ones)
healthunlocked.com/thyroidu...
SeasideSusie humanbean SlowDragon bluebug helvella