So it might effectively turn T3 into T4 again? From my understanding the T3 is the hormone with 3 iodine molecules and T4 is Thyroid hormone with 4 iodine molecules.

The caffeine thing is interesting. I think I've been trying to compensate for low thyroid all these years by drinking lots and lots of caffeine. But, if I'm reading that correctly, that would cause my TSH to stay low and T4 high, even while my T3 is low.

I think it is time to try to give up the caffeine again. *sigh*