Re: When is it time to add Cytomel to Synthroid ?
If you had RAI in September, I'm guessing it took you at least a month to go hypo - maybe longer? You need to realize that's just a teensy blip in the thyroid treatment timeline. It takes time to find the right med and the right dose. Testing, tweaking, time, thyroid, T4, T3.... Lots of Ts.
You would need Cytomel if your body doesn't convert T4 to T3 easily. Most people have some degree of difficulty in that area, but it's too soon for you to know if that's the case. Once you build your store of T4 to an adequate level - at least midrange - and you have remaining symptoms and still don't feel well, it might be time to seriously think about the possible need for some T3.
You also should know that your TSH can remain low for a good long time following RAI. It isn't indicative of much at this point, and it shouldn't be relied on for med dosing. Much better to watch FT4 at this point, and perhaps push for FT3 in the future if the Synthroid doesn't do the whole job for you.
Hang in there... It will get better... with time!