Official changes in B12 reference levels?

My son had his B12 tested on 27th March and the reference range was given as 190 to 660 ng/L. Had it tested again on 1st June by the same lab and the reference range is now given as 180 to 999ng/L with a note saying 'Please note revised reference range from 31st May'.

What's going on? Has there been some directive to drop the lower level so that fewer people get diagnosed? Has the lab got a new machine?

Seems odd that the 'normal' level should be lowered at a time when it seems that the medical profession is finally becoming a little bit more aware of B12 deficiency.

8 Replies

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  • Most likely explanation is that they're usually nag a new assay.

  • I support this reply but I wonder what fbirder means by ' nag' ! LOL - love you fbirder!

    My understanding is that when a pathology lab changes its range, it means that they have changed the type of test or updated the version of the test (assay) that they are using to test and measure that particular aspect of a blood sample.

    So it is not necessarily to lower the number of people who prove positive to a condition and qualify for treatment.

  • I must be having a particularly 'thick' day. I always thought that reference ranges were determined by taking samples from a healthy population and I cannot see any reason why a reference range should change from one lab to another or one county to another. If the lab is using difference equipment, chemical reagents or whatever, how would that change the reference range, they are still measuring ng/L.

  • The different labs using different machines will produce results in pmol/L (or ng/L). But their sensitivity will vary. A very sensitive machine, using a good assay with good analysts might well get different results from a lab using an older machine with poor analysts - for the same sample.

    What you need to realise is that 150 pmol/L is a very small amount. If you took a bottle of aspirin and dissolved it in an Olympic-sized swimming pool then that would be about the right concentration.

  • Thanks, I do realise that we are dealing with very very small amounts and I also realise that different labs will produce different results depending on machine/assay, but my query was really about the reference ranges.

    Why should reference intervals change with different labs and different regions. Why is it not possible to stick with one reference range for all labs in the UK.

  • Our labs (I'm in the north east of England) have the range from 150-1000

    My b12 is 152 I'm hashimotos and elderly doctor won't even acknowledge there might be a problem even though I've been supplementing with Centrum multi vitamins for years and my b12 has dropped since last tested

  • I may be missing something about reference ranges but this is what I have been trying to say, if you moved somewhere else, or your doctor used a different lab you could well be under the reference range. But this also highlights the fact that there is a margin of error in the assays because of the methods/machines used - I would just have thought that knowing this, doctors would be more willing to treat someone who was 2-3 ng/L from being deficient and not being total slaves to the readings, as they are with TSH. Surely common sense must prevail and they should be taking symptoms etc into consideration.

  • Absolutely agree, it is complete nonsense that different reference ranges are used. In my case my (after 2 years of non-diagnosis) a neurologist in Glasgow finally tested my B12 at 195 ng/L. Fortunately the reference range used by the lab used a lower level of 200 so I was "just" below the level and after a little argy-bargy with my GP was able to get the injections. After 3 or 4 injections many of the problems I had had for the past two years began to abate and I now feel so much better. Still a way to go as the diagnosis took so long that I have neurological problems that may take some time to resolve (if they are not permanent).

    What is concerning is that if the lower reference level had been 180 or even, god forbid, 150 (as some others have reported) then I would have had little chance of persuading my GP to treat me. I would have been told that my levels were 'normal' and sent on my way. It really is ridiculous that different ranges are used in different parts of the country.

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