Have you done a search of the archives? Try putting Kellon Thyro-L into the search box and you will find numerous posts in which Dr. Kellon has discussed and answered questions on Thyro-L. I just did a quick search and a post came up where you asked and got an answer to a similar question as you just posted.
BTW, who recommended supplementing Thyro-L to Jesse? Your new vet? I thought the vet said his BCS was a 4 + and he looked great so why the Thyro-L recommendation?