My philosophy is - assume it's the thyroid until proven otherwise. My GP was adamant that the downhill slide which began as I turned 61 was age (Although I had been working 1 year before and had a clean bill of health from my occupational medical ).
This, despite the fact that the downhill slide coincided perfectly with his reducing my thyroid meds from 150 to 100 - 8 weeks afterwards, to be exact. Down to the right dose, according to the blood tests.
Oh no, NO connection.
I am now much closer to optimally treated. (Well, over-treated according to my TSH, but NOT my T3 which the GP ignores.)
Guess what - the 'arthritis' in my knees seems to have healed itself, my cholesterol has fallen from 10.2 to 6.7 without statins, I have lost two stones in weight and I can walk upstairs without cringing in pain. I have started knitting again and my 'depression' has gone, I now actually look forward to going out, instead of being a recluse.
I am 69 now and I am better than when I was 61 - in fact, I'm better than I was at 59, come to think of it.
Not connected with hypothyroidism? pull the other one!