You raise good points, thank you. I had stupidly omitted, from my OP, the thyroid results from that batch of tests:
Free T3 5.2 pmol/L (3.5 - 6.5)
Free T4 23.0 pmol/L (11.0 - 23.0)
TSH 0.99 mu/L (0.35 - 5.5)
For the benefit of others reading this who are going through the same thing:
I am fortunate to have private medical insurance. In the UK, however, you're required* to see your National Health Service ("NHS") General Practitioner ("GP"- family doctor) practice who then write you a referral letter for you to see the specialist of your choice thru the private medical scheme. (Yes, we think that makes no sense either
Yesterday, I went to see a GP with some trepidation - as I was expecting a battle for referral. On the contrary - the Dr couldn't have been more helpful!
She was completely sympathetic, mentioning that her husband has hypothyroidism and empathising with the symptoms I was describing. She investigated the specialist I'd chosen and thought he was a great choice. She ordered additional blood tests (Vit D, ESR and a bunch of others I can't remember without the notes) so that I could take them all with me on the day - and she wrote the referral letter and a handy summary for him of everything so far.
Of course we had a discussion about 'symptom versus problem', and I made the point that I chronically abuse stimulants and sugar in order not to feel like crap - so absolutely accept that it may be lifestyle related, BUT we agreed that my fragility after even moderate exercise that's surrounded by optimum nutrition and sleep is at least worth investigating. (for example - wary of KSMan's pointer towards 'adrenal fatigue', I've cut out all stimulants and sugar, and have spent the last three weekends horizontal on a sofa, which is boring and a bit sad)
So - next stop, the endocrinologist this weekend. I'll post back findings/ experience here.
*yes, there are ways around this, before someone jumps to correct me - however seeing your GP for referral is the 'normal' process