Measurement Ranges

After another poster showed test results a little earlier, I realised the stark difference between regions on what is the recommended range for various samples.

In my area the range for B12 is 180-914

The range for Folate is 3.1-20

Not that serum B12 is that accurate, but I would be deficient with a reading of 170 but fine in another area.

Are there any significant anomalies in the range across the country, perhaps even the world?

I know the lower limit for B12 is higher in Japan and Canada.

11 Replies

  • Hi, GGourmet...yes the ranges are quite a bit different depending on where you live. Sleepybunny posted a thread 2 years ago regarding that, it was a private post so look for a post by Sleepybunny "Reference ranges for B12." I can see it in the "Related Posts" → hopefully you can too. :)

    Also, the ranges given for any analyte can vary depending on the type of machine used, the reagents used and so on. When chemical tests are done, the equipment is first calibrated with standard solutions, those techniques can vary. Just my experience from working in chemistry.

    I'm convinced I'd feel much better if I lived in a different country or if I was a sheep in New Zealand. :)

  • They can also vary because of the units used - important that you don't just give numbers but also give the units to used - it's like quoting a volume without saying whether it is litres or pints.

  • That is true but these vary by a factor of 1000. Microgrammes per ml is same as milligrammes per litre. So in most cases just the number works and most testing labs around the world appear to only use the metric system.

  • GGourmet, this isn't about what denominination of a metric unit is being used to express the results this is about two very different ways of measuring the concentrations in blood - ng/L v pmol/L - one is expressed in terms of weight and the other is expressed in terms of number of molecules. Because the weight of molecules don't change that means there is an arithmetic difference between the two units of measurement - but it will vary depending on what chemical you are measuring. With B12 the the factor is about 1.355 but with less complicated compounds it will be much higher.

  • Yep, I quite agree, although I have never seen that conflict so far. One measuring volumetric density and the other mass density. I had always believed that reporting was standardised, so perhaps not then.

  • You are ignoring the pg/mL and pmol/L difference - which in the case of B12 is fine enough not to be obvious but large enough potentially to be significant.

    1 pg/mL = 1.355014 pmol/L

    (Mole is an SI base unit.)

  • As before, I am yet to see molar density reporting in this space. Perhaps yet again another example of the fractured reporting across the NHS alone.

  • I have seen both used right here and over on Thyroid UK. Not everyone is quoting an NHS result. And the pathology harmony initiative seems to have disappeared off the face of the earth. Well, they didn't renew the domain which suggests no funds.

  • According to my recent blood test, B12 range in my area is 145-914 ng/L

    Folate is similar at 3.00-20.00 mcg/L

    The cynic in me wonders if some trusts change this value to adjust the treatment they have to give, rather than deciding what the evidence suggests is a good level.

    It seems rather antithetical to the idea of a National Health Service, with National guidelines produced by NICE (The clue is in the N!), when local areas can ignore it and set their own standards?

  • Yep! But how to get change? CQC might be a starter, or NICE themselves.

  • In my area it is 110-900. So at 118 I was regarded as being within range.

    Interestingly my daughters cat has just been diagnosed with low B12,and folate. Not sure what the range was for that!!!!!!

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