What that means is that the measure of TSH is extraordinarily sensitive, as was pointed out by many of the speakers earlier, but sensitivity does not mean accuracy. It does not convey an idea as to really what the bioequivalence is. It may be the ultimate desire to achieve this, a certain level of TSH, but it cannot measure the dose necessarily, and what we have to ask ourselves ‑‑ and this is really the question I'm coming to ‑‑ is, what are the main variances or differences?
To me, the greatest difference is in different patients that will provide the biggest difference. The next one may be different formulations, then different batches of the same formulation, and different times, the changes over time within the same patient. That may be in the same order of magnitude in terms of a variance to the others.
So if we design our tests that are extraordinarily sensitive to small changes in the dose and that's granted, I do think that's truly the case, it may fail many of the formulations, whereas the more important aspect is what is the variability within the same formulation, etc.