The simple response to that statement is because we are unique. Even identical twins are not really identical but each has unique features compared to their twin. So why is this important for our doctor's to consider? Well our uniqueness means that we may not fit within a statistically derived range on blood tests or even on physical parameters like blood pressure or heart rate. Even the odds of illnesses may not apply to any one of us just as the likelihood of side-effects may also not fit us. Since nearly all the parameters that doctor's use to evaluate us and our health are based on statistical averages, this guarantees that what is normal for some of us will be outside the normal ranges as approximately 5 to 25 percent of us will fall outside this range. In addition, it is helpful to know what our values are when we are doing well and do not have any symptoms as this will show what our normal values are. This is a problem as many of these lab tests are not part of wellness screening. As an example, TSH [thyroid stimulating hormone] tells you how much hormone your thyroid is producing, based on how much TSH is required. If you do not have TSH values from when you were healthy, then it is harder to interpret whether your recent TSH value is normal for you or not. My point is that a statistical averarage may not be your average. The good news is that hypothyroidism is a clinical condition that is diagnosed by symptoms you are having and is not diagnosed by your TSH level. The bad news is that the TSH value is often used to decide if your thyroid is ok, no matter what clinical symptoms you have.
What can you do? You can be an active participant in your health care. In fact, if you are not an active participant in your health care then you are much less likely to receive good health care. Doctor's need your input to provide good care. So what does being "an active participant in your health care" mean?
I'd recommend that you:
Remember to be grateful that you are in charge of your health!