Thyroxin T4 is ideally used with Eutropin (HGH) as it has been shown that T4 level are reduced during the use thereof.
The great thing about T4 is that it is more difficult to overdose it. T4 is converted to T3 by your body and is safer to use than T3 itself. The reason being is that your body will convert T4 to T3 and of course, your body will not overdose itself and will only convert the optimum amount to T3.