You wouldn't need to invoke the idea of 'hormone resistance' because TSH and T4 tests normally used to diagnose hypothyroidism don't measure the active hormone - T3. T4 is just a prohormone with very little direct activity on metabolic rate.

In primates, metabolism is regulated primarily in the liver by T4->T3 conversion, so if this is inhibited for any reason it will suppress metabolism without showing up on those tests. Low calorie intake, and poor nutrition are known to cause this (e.g. Euthyroid sick syndrome). In cases of poor liver conversion, supplementing T4 can actually make symptoms worse, as it will further suppress metabolism by lowering the small amount of T3 production from the thyroid (via the TSH feedback loop).

I assume you have heard of Ray Peat? I personally had good luck applying his ideas to increase my energy levels, and my pulse, body temperature, and cold tolerance raised as well - without supplementing thyroid. His general idea is pretty simple- just look at what conditions and nutrients maximize T4->T3 conversion, and provide them (low stress, high nutrient diet).

Broda Barnes work is very interesting. It blows my mind that he published a paper in The Lancet showing that desiccated thyroid lowered cholesterol levels and seemed to prevent cardiovascular disease in his patients, and that it remains virtually un-discussed and uncited (http://www.ncbi.nlm.nih.gov/pubmed/13796871).

Well, talking about it, admitting doubt, those sorts of things would be a start.

Before this became something routinely done on the NHS, it would need cast-iron proof sufficient to convince NICE, and I approve of that wholeheartedly. But there are a lot of smaller steps between 'suspicion' and 'certainty'.

Can doctors just try to give things like dessicated thyroid to their patients?

They used to hand it out routinely, back in the days when hypothyroidism was diagnosed by symptoms (up to ~1965), and everyone thought it was as good as medicine got. There seems to have been huge pressure to stop doing that, including striking people off, and I wonder what evidence was used to support those processes. If there is any, that's what I'm looking for.

Now, I think you might be in serious trouble for not following the guidelines. The guidelines for CFS say: 'don't use thyroxine'. But they don't give a reason or a reference. It's mad.

In America, apparently, doctors are much freer to try things, and some of them do, in full knowledge that endocrinologists disapprove, and it works.

But actually, desiccated thyroid is also available as a 'food supplement', and you don't need a prescription for it in England or America, so chiropractors and osteopaths and homeopaths and naturopaths and mad people on the internet and the like are free to tell people to take it. And they do. And then they write books about it. Just Google!

Well, it's been done and the results, as you are well aware of, are inconclusive.

Actually, I'm not well aware of that. I really haven't found anyone saying 'We tried this on people with hypothyroid symptoms, and it just made them hyperthyroid, as you'd expect." Everyone who's tried it seems to think it works a treat. I'd love to see counter-evidence if you can find any.

The worst anyone has to say is: "It works most of the time, but often we find that there's something adrenal going on as well, and in those people we have to fix both".

The question answered inconclusively was "If we hand this out to fat, tired people with dry skin, does it work?". And the answer to that is: "On average they can't tell the difference between that and placebo.

But they also proved that healthy people can tell the difference on average, and they don't like it. Presumably because it gives them hyperthyroid symptoms, which aren't very nice.

Everyone who's ever tried fixing the clinical diagnosis of hypothyroidism with any kind of thyroid therapy either seems to think it works, or hasn't written about it on the internet or in the medical literature.

That's a big claim. I'm making it in bold on Less Wrong. I expect someone to turn up some evidence against it. I would love to see that evidence.

I find this bewildering. I thought that the problem would be complicated and difficult.

And at the moment I'm just staring in disbelief. What the hell is going on?

Squirrel, it's bloody dangerous. I'm arguing that it should be investigated, not that everyone who feels tired should start glugging hormones.

But it's not unfounded. I've found loads of anecdotal and circumstantial evidence, and very little against (hot daytime fibro-turks is the most surprising thing, and the alternative people seem to think there's often also adrenal issues, but usually secondary). And now two studies from the 'proper' literature.

And I'm fairly sure that endocrinology has never bothered its pretty little head about type II versions, or the accuracy of its wretched TSH test, despite the example of diabetes staring it in the face.

I'm as sure as I can be without formal trial (so maybe about 25% confident?). But I'm now certain that the lack of investigation and of formal trials is inexcusable negligence. J' totally accuse.