T Nation

Lab Reference Ranges

How do labs come up with different reference ranges when they use the same measurements? For example my last labs were sent through ARUP labs and their reference ranges are:

TT 400-1080
Bio Free T 47-244
Free T 1.6-2.9
E2 12-41

Their ranges seem a lot more realistic than Quest.

Also by these numbers my first set of labs a year ago would have told quite a story. TT 379 E2 41. Those were both within range on Quest labs and the endo told me I’m fine and have a nice day. Maybe get some Zoloft… I wonder what he would have said with these ref ranges? (Probably the same thing)