Conflicting Lab Ranges

[cristiana]

I've just had an operation and the hospital ran some blood tests before I went into surgery. 

My Haemoglobin was flagged as just above range (15.2 - normal lab values for women cut off at 15) and my Red Blood Cell Count was 5.18 (normal lab values for women cut off at 4.8).   

Looking at my coeliac blood tests over the last eleven years I've noticed these readings have been even higher (Haemoglobin was 16 once, Red Blood Cell Count was once 5.4);  in that time, both Haemoglobin and Red Blood Cell Counts these readings have fluctuated greatly and have even gone down to within normal levels, too, which is why, I suspect, the doctors don't seem to be concerned, although my gastroenterologist won't prescribe me iron to stop me becoming polycythemic. 

What I don't understand is that over the time I've been a coeliac the cut-off points for both readings have decreased from 15.5 to 15 for Haemoglobin, and 5.8 to 4.8 for Red Blood Cell Counts, so had I had those tests done, say, five years ago, I would have been within the lab's range.     

Does anyone know why this happens?  Do lab results change according to latest research findings?  Is it to do with new machinery?  

Thanks!

[RMJ]

Normal hemoglobin levels are defined by looking at results from thousands of healthy people and doing appropriate statistics to get an appropriate range.

Those calculations may be revised occasionally, or different in different countries, or a lab could have their own range…

Here is an article evaluating the World Health Organization range:

Evaluation of Hemoglobin Cutoff Levels to Define Anemia Among Healthy Individuals

You didn’t ask about celiac antibody normal ranges, but in case you look at those, or someone sees the thread title and wonders about them, they can be very different from lab to lab. The units for reporting celiac antibodies are not absolute - they’re different for each test manufacturer.  Hemoglobin results are given as weight per volume of blood.  Celiac antibodies are units per volume of blood, with units standardized within each test manufacturer but not between manufacturers.

[cristiana]

Thank you RMJ, that makes sense.  I think the cut-off point for Hb levels at the lower end  haven't changed since my blood was first tested pre-celiac diagnosis  ten years ago, but the higher levels have been adjusted down, certainly in my area.  I suspect this is possibly a WHO revision, or similar.  It might explain why perhaps the doctors who have been treating me don't appear too worried when they see I'm a bit over,  if they've lived with the older levels for years!

Edited December 6, 2023 by cristiana