As I have a diagnosis of both autoimmune underactive thyroid plus also ME/CFS can anyone explain to me whether the dysfunctional thyroid impacts on the metabolism of energy OR does the dysfunctional metabolism impact on the thyroid function? (I have had mitochondrial tests done which indicate problems with metabolism via the Acumen Lab in the Uk - I know these are not accepted mainstream but assuming that there is some truth in the results........) Or is it both of them in a vicious circle? Or is it as I suspect, a lot more complicated that either of these! Just trying to get my head round this as the NHS (health service in the UK) have insisted that I had speeded up my metabolism too much by being on T3 only (Liothyronine) with suppressed TSH and contributed to my osteoporosis, and so they believe that now I am on T4/T3 and the FT4/FT3 levels are falling that I am now at the correct metabolic rate, even though of course I don't feel I am! The nurse just tells me that I am used to being at that higher rate so I am not used to it - hard to believe this really as I am now struggling for energy again.