Update on inconsistent ferritin results between NHS and Medichecks

[jsy_girl]

This post is an update on post:

healthunlocked.com/thyroidu...

Whereby i had 2 NHS ferritin tests and 2 medichecks ferritin tests with consistently inconsistent results.

and these people especially wanted the update:

SeasideSusie

SlowDragon

and humanbean i mentioned it to you in a post too

Medichecks have responded today:

Many thanks for your enquiry about the ferritin results that you have received from ourselves and the NHS. Reviewing the NHS results these have a different reference range with a higher upper limit. This suggests to me that the NHS laboratory is using a different analyser platform to our laboratory. Variation in measurements between laboratories is a normal phenomenon and can be seen in the results of the external quality assurance schemes that all laboratories take part in. This involves all the laboratories performing the same test on identical samples with a known concentration of the substance being measured. The results from the participating labs are compared, as are the results from the different analyser platforms that the labs use. Analysers from different manufacturers do tend to return consistently different results when they are compared.

Our laboratory uses the Roche / Cobas analyser platform which is one of the most widely used and reliable platforms worldwide. Looking at your results the NHS results consistently return a higher result than the Medichecks results, which makes me suspect that we are seeing a combination of inter-laboratory variation, and the variation between analyser platforms that is outlined above. The reference ranges also suggest this, the higher limit on the NHS reference range suggests that the average result for women of your age (ferritin reference ranges for women vary according to whether they still have periods or not) is higher when measured on their platform. If you reply to this email letting me know which hospital processed your sample I can explore whether the reasons outlined above account for the difference.

We have discussed your results with our laboratory and they have advised that there were no issues with either their analyser or your sample that would explain the difference in results. So in summary I suspect that the difference we are seeing is the result of the variation in results seen between laboratories and analyser platforms.

- - -

I have responded:

I’m not sure that’s right because if the NHS range is wider you would expect like for like that my result would have been higher with the NHS test. You also say my results are higher from the NHS and this tallies with your expectation, but my results were lower from the NHS. So much so that my GP is concerned by them and prescribing me ferritin tablets. The results from medichecks are higher and classed as “good”. This concerns me because I am relying on your tests in the iron panel to assure me that my serum iron isn’t too high and that I won’t suffer iron poisoning as a result of supplementation.

---

Does their email make sense to you? Or does my reply seem fair?

I will keep you all updated!

[SeasideSusie Remembering]

jsy_girl

Thank you for posting this.

What I don't understand is that the units of measurement for both private lab and NHS are the same (in my case) so why the difference in the range.

Also, it seems that Medichecks range is always the same when members post their results (13-150) regardless of whether they are pre or post menopause.

My results are always lower with the NHS test which has a much wider range (15-300).

[jsy_girl in reply to SeasideSusie]

I’ve added your points to my reply. Thanks

[jsy_girl in reply to SeasideSusie]

The response...

Firstly may I offer my apologies for mis-reading your email, I would like to reassure you that the issues regarding inter-laboratory variation, and variation between analyser platforms still applies. After the menopause ferritin levels in women will tend to rise. Our doctors will take this into account whether someone has been through the menopause when they are interpreting results, although the range supplied by the lab may still be the pre-menopause range.

In answer to your question about the units being the same and the reference ranges being different, reference ranges differ between laboratories because labs will calculate their own reference range to suit the population they serve, and the analyser platform that they use. They do this by taking the mean of the results for a healthy population, and then setting the boundaries of the reference range two standard deviations from the mean. They do this because the sources of variation between laboratories mean that a single standard reference range cannot be applied across all laboratories. There are some exceptions to this, such as the HbA1c blood test used in monitoring diabetes. In this case a great deal of work to standardise measurement across laboratories and across international borders has occurred, and a standardised reference range can be used. For most blood tests it is recommended that laboratories develop their own reference range.

I hope this answers your questions, I'd be happy to arrange a call if you would be easier to discuss your queries.

——

This doesn’t seem to answer the point where he seems to assert that this explains why my nhs tests are higher when in actual fact my nhs tests are lower. You’d think with a higher/wider range my results would be like for like higher than the medichecks result. Anyway I think he might have missed half of my reply as it was across 2 emails. I’ve replied and also said that yes unless he can explain this then a phone call might be helpful.

I might try thriva for my next iron panel!!!

[SeasideSusie Remembering in reply to jsy_girl]

jsy_girl

Well done on continuing to pursue this to get a satisfactory answer.

This doesn’t seem to answer the point where he seems to assert that this explains why my nhs tests are higher when in actual fact my nhs tests are lower.

So, exactly the same as me and this isn't explained in their response.

Just as a point of interest, regarding the range for pre/post menopausal women, the ferritin range for men is supposed to be wider than for women. My son, same surgery as me, has exactly the same ferritin range - 15-300 - as myself.

I might try thriva for my next iron panel!!!

I don't think it will make any difference. Thriva use County Pathology to process their tests, as do Medichecks and Blue Horizon when I use them.

[jsy_girl in reply to SeasideSusie]

I just think if the answer from them is inter lab variation and variations by platform analyser then they’ve got a problem which they are not admitting to currently because their results suggest I am 36-43% through the ferritin range but the NHS results suggest I am c 8% and thereby giving you entirely different information for next steps. I am also still concerned he has got the results the wrong way round and is thinking the NHS results are the higher ones which makes more sense if the range is wider.

Don’t worry I’m not one for giving up!

Yes I’m not convinced there are different ranges based on menopause. Oh that’s annoying re thriva. I think if my iron levels aren’t much higher at my December review I shall ask my GP if they can do an iron panel on NHS. That will be an interesting comparison too.

Thanks for your reply as always. Will be interesting to see if I get a phone call, just hope he doesn’t try and bamboozle me haha. If I could get it set up as a conference / zoom / teams call would you be interested to join it?

[SeasideSusie Remembering in reply to jsy_girl]

jsy_girl

If I could get it set up as a conference / zoom / teams call would you be interested to join it?

Unfortunately, I don't have the technology for that. I have a PC but my monitor has no sound (nor camera). However, I'm more than happy for you to use any information that I have given you, I can give you the exact numbers if you want.

[jsy_girl in reply to SeasideSusie]

No problem just a thought!

[jsy_girl in reply to SeasideSusie]

I've had the call - he was very helpful and apologised that he had misread my NHS test results and switched them around in his head.

He's requested the external quantitative assessment on results by lab to see if generally there is a split of results by lab/different analysers.

And he asked would I do another test which they will send to a different lab from the one they sent it to before but that still use the same platform analyser as the one before - that way they could see if its just that one particular lab, or more likely if its the same result as before it will be that its a variation between the platform analysers. Medichecks do use a different platform analyser (canon roche) from the NHS ( sounded like Beckman Coulter).

I said yes of course, so we'll see what that throws up. We are speaking again in a fortnight.

[SeasideSusie Remembering in reply to jsy_girl]

Thanks for the update, please do let me know how this all pans out. I have a Medichecks Iron Deficiency Check test here but don't intend to use it for a while, I just bought it when their 20% discount was on, ready to use when I next check my ferritin level (I'm trying to raise it).

[jsy_girl in reply to SeasideSusie]

(I'm trying to raise it).

Arn't we all 🤣

Yes I will do - it would be good to know how we should interpret the results which was the essence of what I was asking him.