Hi, I would recommend being honest and as others suggest being prepared with facts to fight your case. Fight you may well have to depending upon your endo.
We recently went to endo for my hubby Bob to ask them to re-prescribe T3 after taking him off it and they kept 'going around the houses' asking the same questions over and over with me providing them with answers from my notes rather from NHS info. I challenged them on quite a few points. They weren't really listening.
I showed them the Dr Lowe critique thyroidscience.com/Criticis... which was dismissed as 'some people will always disagree'. They tried to say Bob's deterioration in health should be investigated by GP to find a cause. I said scientifically if the only change that has been made is in his medication (coming off T3) then the greatest likelihood is it's coming off T3 that has affected his health - they wouldn't accept it.
They could not accept that his rapid weight increase being back on T4 was more of a concern regarding potential heart, BP and diabetes issues than being on T3.
They kept twittering about worrying about T3 causing peaks and troughs in blood - so what? This happens naturally in the body and homeostasis balances. Bob's T3 was at the higher end of normal when blood test taken just after he'd taken a T3 dose and at the lower end of normal if he was due a T3 dose. Can't see what's wrong with that! I then asked point blank if they were refusing to re-prescribe T3 and they said 'yes'. At that point I said we might as well leave. Bob was warned about self-medicating and I just couldn't be bothered to say that if that returns him to health that's what he'll do. I wish you more success.
Bob was the only patient in Grampian region on T3 and only got it after I 'bullied' our previous GP into prescribing it. She could then see it improved his health but she has now left the surgery and another GP referred Bob to endo because he was on T3.