What is this T3 medication??
T3 only medication is the main bio-active thyroid hormone. Brands include Cynomel (Mexican), Cytomel (American), or Tertroxin (UK). The Chemical names for this are Liothyronine sodium or triiodothyronine. This Wikepedia article gives you more information on what T3 is. There is also more information here and here
Changing over to T3 only, and adding enough to suppress your own thyroid's production of hormone, eliminates T4 from the body. Without T4 no more RT3 can be made and hence if you want long enough the RT3 circulating in your body will decay or be excreted and you will greatly improve the ratio.
Fairly early on the lab tests will show a great reduction in RT3 but don't hurry to change back to Armour or T4 as it takes longer to clear the T3 receptors that are blocked up with RT3.
It typically takes 12 weeks of T3 only for this to happen and then the results are sudden, you can find overnight that you need to drop your medication almost completely for a day or two and ramp back up again to around half the level that you needed before to stop feeling hypo.
I will talk more about dosage on the next question.