Laboratory Referenre Ranges


Eleanor Kellon, VMD
 

It's very important to recognize that reference ranges are not the same thing as normal ranges. Reference ranges are a statistical range - the average +/- two standard deviations off the average.  This graph https://magoosh.com/mat/files/2016/05/Bell-Curve.png shows + or - standard deviations off the average and how those will account for 90+% of the test results but that does not mean those results are actually normal. By using reference ranges you greatly increase the chances that your interpretation is not negative, but many positive results will be missed. The chances these ranges will be off is further magnified when you recognize that horses/ponies which appear to be "normal" may very well not be normal and in the case of insulin the diet the animal ate, and when they last ate it, is not considered. When the references include animals that may actually not  be normal and may have recently eaten a meal high in sugar and/or starch, the standard deviation gets very wide and the whole range ends up meaningless.
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Eleanor in PA

www.drkellon.com 
EC Owner 2001


 

As a practical matter for case history purposes, many lab reports often make no mention of Lab normals (the language on the case history form). What should our members enter in the case history? Cornell, for example, uses the term Reference Interval and discusses reference ranges.
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Cass, Sonoma Co., CA 2012
ECIR Group Moderator
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Nancy C
 

Hey Cass. 

For the new CH project, we are using Lab Reference Ranges.

See also:  https://www.ecirhorse.org/FastingInsulin-LabRefRanges.php

Why Reference Ranges are not Normal

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Nancy C in NH
ECIR Moderator 2003
ECIR Group Inc. President/Treasurer  2020-2021



 

Thanks, Nancy. Reference ranges are what we see on the reports, so that change in terminology may resolve at least one source of confusion. 
--
Cass, Sonoma Co., CA 2012
ECIR Group Moderator
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