On a steep learning curve……..bear with me!
I am aware that when you get a print-out of your test results the lab ranges are usually in brackets (lowest to highest) next to your actual results. I initially assumed that these ranges were “standard”, but I’m also picking up now that this is not necessarily the case.
I read today that “to create a reference range, a number of volunteers (usually over 120) are matched for factors such as age, gender and ethnicity, and the analyte of interest [had to look this up – the constituent that they are interested in - like Ferritin] is then measured”
What I understand by this is that a middle-aged female patient would be likely to have her blood test results measured against a different set of lab ranges than say a teenage male patient.
What I don’t get is why does the range differ from lab to lab? or does it....? Environmental factors?? Or do different labs use different scales? Or do scales change??? I recently received a print-out which seemed to suggest this (i.e., for the last 13 years my Hb has fluctuated between 9.9 and 14.8 - a series of 29 blood tests - then suddenly in March 2013 it shot up to 122. This latest March result did come with some ranges (115-165) so what was going on for the last 13 years?)
Most importantly, does this also mean that looking on the internet for standard ranges is a bit of a waste of time??
I AM learning that the simple solution is to always get a print-out.
Any help gratefully received.