Who decides what's 'normal' in medicine?

Overview of the thyroid system (See Wikipedia:...
Overview of the thyroid system (See Wikipedia:Thyroid). To discuss image, please see Talk:Human body diagrams (Photo credit: Wikipedia)
When you go to the doctor and he does tests, ever wonder how “normal” is determined?
Ideally normal should be “optimal.” But, what is optimal for you is not always optimal for me. And, sadly, how we determine “normal” in standard medicine has nothing to do with what would make our bodies’ the healthiest.

Take thyroid levels for example. When labs “norm” the studies, they get volunteers – many times hospital and/or lab employees, ask them if they are well that day and make them part of the random sample. Now, of the 50 or so employees used to norm the test, some may not be normal. In fact, due to genetic drift, lack of iodine in the diet, bromine exposure and other factors, a great number of people’s thyroids are not working normally, and they are actually hypothyroid, but haven’t been diagnosed as such. Nevertheless, these abnormal people become part of the pool of people to determine the normal range of thyroid. Therefore the “normal” range actually is skewed to the abnormal.

Continuing with the case of thyroid, TSH is a measure of thyroid function, and as the thyroid fails the TSH gets bigger, We know from studies in the heart as well as bench analysis that if the TSH is above 1, the thyroid function – its effects on different body tissues, is abnormal. Cardiac output, the ability of the heart to pump blood diminishes with a TSH above 1. Yet our lab range of “normal” continues to be 0.4 to 4.5 – a range so broad as to include a lot of sick people.

Secondly, take the numbers for male testosterone levels. Lets say a normal 25-year-old has a testosterone of over 150 on average, a level found in young, virile, healthy males. Now you, the patient, are a 55-year-old male who has noticed lack of energy, increasing abdominal girth, inability to get benefit from working out and loss of libido. You just don’t feel like yourself.
So you go to your doctor and ask, “Doc, could it be my testosterone level?”

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