This is an excerpt from the following link:-
8. Misunderstanding and Misuse of the broad laboratory reference ranges (misleadingly called "normal ranges"). These
are not optimal ranges--not even close. They are 95%-inclusive population ranges--they include almost all of a group of "apparently healthy" adults who were not screened for symptoms of deficiency. Only the bottom and top 2.5% or "low" or "high". So if a person's hormone level is near the bottom of the range, he/she is in the lowest 5 to 10% of all adults! How can a physician say that's "good enough"? Even when someone is below a population range, in the lowest 2.5%, the doctor will typically repeat the test to see if he can get a "normal" result. Only If the level is still low, will he give them some hormone replacement to "normalize" their levels! This is a game of population statistics. It is not clinical medicine. In fact, much more than 2.5% of the population has suboptimal levels due to aging, endocrine dysfunction, and disease. Because so many persons have low levels of some hormones, the lower limits of the ranges are sometimes even listed as "0" or undetectable! Dr. Lindner calls this
unthinking practice "Reference Range Endocrinology". The doctor glances at the lab report and if there is no bold "H" or "L" for "high" or "low" next to the hormone level, declares that there is no hormonal problem--even if the patient has symptoms and the hormone level is near the bottom of the range!
There are no cut-offs in Nature. Hormones work on a continuum from the lowest to the highest levels. One cannot draw a line and say everything above this line is "normal", and everything below this line is "disease". There is no substitute for medical judgment in deciding who will benefit from hormone restoration. This question ultimately must be settled by a clinical trial--supplementing the hormone to higher levels/effects to see if it helps the patient.
9. Belief in many HORMONE MYTHS, such as:
Restoring a hormone that is below the reference range to any level within the reference range is good medicine. (In fact, given how the ranges are constructed, the lower thirds of many hormone reference ranges represent hormone deficiency for much of the population, and many studies show the benefits of higher levels within the ranges.)