with a 4.8 more than like t3 and t4 numbers are lower end of range. I would think you would want free t3 and free t4. But I would go further and test for thyroid antibodies. I found out I have high thyroid antibodies, they called it Hashimoto's, anyways we are looking at other ways to treat it right now, and possibly remove what is causing the elevated antibodies.
Also to consider you might have high tsh meaning your thyroid is having to output a lot, but if you don't have symptoms and t3 is in a good range, might not be worth messing with. Mine are just slightly below where htey need to be, so if we can remove some of the stress on my system might be ok. Reason why I suggest getting a big picture so you aren't just on meds rest of your life. I tried synthroid mind you and hated it for the 6-7 weeks I was on it.