'Estimates of average normal secretion for euthyroid humans are 94-110 µg T4 and 10-22 µg T3 daily (308). The thyroid may also convert some T4 to 3,3’5′-T3 (reverse T3) within the thyroid.'
That, I believe, is equivalent to 3 - 5 grains NDT. So, my 6 grains wasn't such a high dose, after all!
Very interesting. I take 100 T4 and 15 to 20 T3 and have never understood why huge chunks are taken off people's T4 when 10mcg T3 is added. No wonder they can never find a human study showing that the combo of T4/3 is preferred by patients. They are never on enough of either. I believe Dr Toft began that practice and I really would like to take issue with him over where he got his figures from.
They're just so terrified of you going 'hyper'! In the old, ignorant days, before I found forums, I had a doctor that liked to keep my TSH at 9.5 because, he said, he didn't want me 'tipping over' into hyper. And when I complained about getting worse, he just said, well, I've never know anyone not get better on that dose of levo!!! I told him he probably didn't know many people, then!
It just shows how ignorant about thyroid that they don't know that over-dosing is easily rectified with no harm done.
There is another fairy-tale tied up with the idea of going "hyper" in the minds of some doctors. They compare thyroid hormones to cocaine and heroin. We get a buzz, apparently. (I just wish mine would hurry up and happen - I'm still waiting.) The fact that people who are truly hyperthyroid feel absolutely dreadful never seems to get past the blinkers they wear.
Yes, I've heard about the 'buzz'. Never felt it, though! lol
Yet, they must know that true hypers feel awful, because they have them as patients. I just cannot fathom out how their tiny little minds work - if they work at all!
Oh yes - the "of course you feel better on a higher dose of levothyroxine. Everyone would!" discussion with your GP when he wants to lower your dosage because your TSH is below the reference range (never mind that your FT4 is 12 in a range of 9-22)...
Bah. 
Not true. Being overmedicated feels horrible, stupid man/woman. 
grey, the reference number (308) for those amounts is from a study done in 1971, hopefully testing has improved since then.
308. Fisher DA, Oddie TH, Thompson CS. Thyroidal thyronine and non-thyronine iodine secretion in euthyroid subjects. J Clin Endocrinol Metab 1971; 33(4):647-652.
How much the thyroid produces still seems to be a debated subject. The figures I seem to see the most are around 90-100 for T4 and 5-10 for T3, more or less, kind of sort of. Diogenes next paper may have some relevant information regarding this subject. I don't think we have really solid numbers on what the system can produce through its full normal and abnormal operating range. PR
Grey,
Not sure how you work that out. 
I make it that it is equivalent to somewhere between 1.11 and 2.89 grains (depending on whether we are basing it on T4 or T3, and on low or high end of range.
T4 T3
In one grain 38 9
Low end 94 10
Grains 2.47 1.11
High end 110 22
Grains 2.89 2.44
Six grains comes out at 228 micrograms of T4 and 54 micrograms of T3.
Of course, these figures would only make sense assuming perfect absorption. If that is less than perfect you need to take more to make up for that imperfection.
(Apologies for formatting - we all know HU doesn't make it easy to lay things out usefully.)
Figures based on Armour Thyroid 1 grain tablets which contain 38 T4 and 9 T3.
Rod
Ummm... confession time? I didn't work it out. I pinched it wholesale from another site, trusting that their maths were better than mine. I don't even take NDT anymore. Oh well, back to the drawing board!
.....just had a harrowing time with a Greek lawyer - now returned after driving through rock falls and pot holes in thunderstorms - had a glass of wine - so will have a read in the morning..
thyroid hormones and beta blockers 
Thyroid lab results /medication dose change 
Surprising thyroid results 
Struggling with Thyroid Levels
Thyroid function test
