I have hypothyroidism and have taken Synthroid for it for about 16 years. I do recall a brief time when I took Cytomel for T3. I don't recall why it was stopped, but that was a long time ago (maybe 15 years ago). No doctor thought I needed the Cytomel since and my thyroid functioning has mostly been fine on the proper dose of Synthroid. Neither the Synthroid nor the Cytomel was taken as an adjunct treatment for my bipolar disorder. However, I do know of a woman with bipolar disorder that did take Synthroid (not Cytomel) for those purposes. She didn't even have thyroid problems and was prescribed a fairly high dose. Initially she said it helped her, but after a bit it proved not to prevent serious illness. I believe she was taken off of it after a psych hospitalization. This is not to say it couldn't help some, though.