I too have many symptoms of Hyperthryoidism- extreme weight loss, tachycardia, heart palps, tremors... but am "borderline hypo".
Just started on synthyroid last week. Started out very slowly, 12.5. mcg. and titrating up. So far no problems, but I am still on a tiny dose.
The endo said some pt have both symptoms and do feel better once regulated.... so I am hoping and praying.
Good luck to you!!!!