I went to see my lovely endocrinologist in Sheffield yesterday, and he says (quite rightly) that at present there isn't a "chronologically correct" replacement for T3; we don't yet have a version that can mimic the daily natural rhythm of T3 release. The very short,20 minute half-life of it, means you can't accurately replicate its release by taking the tablets available. However, he also told me that there is current research going on in Sheffield in an attempt to find a better substitute. More power to their elbows I say! I'm reminded again of how lucky I am to have such a consultant working to help me.