Argh. Each lab sets it's own threshold, buy they are all similar. They are set on their own studies and from researching others, and from running known samples on their analyzers. Because analyzers vary, along with variables such as electrical impulses, air temp, sample quality, etc. each performing lab sets their own threshold/values.
An example, for the jurors (!) would be cholesterol. If you have your blood sent to Lab A, their normal range may be 130mg-190mg, while Lab B has set theirs at 140-180. Your doc interprets YOUR results based on the performing lab's values. JB is asking a lot of questions that do not relate to much, and not taking all the scientific variables into account.
Most results under a threshold are not reported or reported as >a number. For example, Less than 45mcg/dl. That means values less than that may not be as precise or accurate as results already proven accurate in THAT lab on THAT analyzer.
Thresholds etc. are really insignificant in this case and are confusing everyone. JB too,