Good questions. So to give a little background for the readers, T4 is inactive thyroid, which converts to T3, active thyroid. GH can speed the conversion of T4 to T3. This can leave you with higher T3 levels, but lower T4. This is usually only a problem for guys that are running higher doses of GH, long term. Lab work is easy and hassle free now days. If you don't have a Dr, you can get lab work ordered online for reasonable prices. After you have been on a higher dose for a couple months, get your thyroid checked. See where T4 levels are and if it is low, most certainly, adding some into your plan would be ideal for off season. Dose would depend on how much you need but figure that 100mcg T4 will equate to about 25mcg T3. As for T3, I would save it for the contest/dieting season