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johnlawrenceaspden comments on A Medical Mystery: Thyroid Hormones, Chronic Fatigue and Fibromyalgia - Less Wrong
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Hi Ryan, thanks. My point is that 'hypothyroidism' is defined by high TSH. I wonder if it's possible to have 'hypometabolism' or 'all the symptoms of hypothyroidism' whilst having a normal or even low TSH and maybe normal levels of the blood hormones too.
to answer your points:
(a) Yes, agreed. Only wrinkle here is that labs often refuse to check T4 if TSH is normal. This has happened to me twice despite my doctor specifically requesting an FT4 test. And I personally know someone who had CFS for years and lots of expensive NHS and BUPA and privately paid treatment without any thyroid test except for TSH.
(b) Yes, but if you've already removed all the people with strange hormone levels (because they're hypothyroid, and so they don't have CFS or FMS), then of course you'll find normal levels in the remaining cases.
(c) Agreed, because hypothyroidism is defined by TSH. My hypothesis is exactly that many cases of FMS/CFS are 'something wrong with the thyroid system that doesn't show up on laboratory hormone level tests'.
(d) Hypothyroidism has lots of famously non-specific symptoms. Do hypothyroid patients sometimes complain of pains in the same way?
(e) that's interesting and surprises me. I was under the impression that exactly that kind of widespread pain was one of the (many possible) symptoms of hypothyroidism. I'll go and look.
Thanks ever so! I've added the explicit hypothesis to the summary. I'll go and see what I can find out about pain in hypothyroidism/fibromyalgia.
a) This is a bit misleading. I've never had a lab refuse to do any test as simple as T4. It's more a matter of how you communicate it. If you as for "thyroid function tests" or "TSH, T3, T4" without clearly explaining, then they will usually stop at a normal TSH.
b) Most people diagnosed with CFS have had their thyroid levels checked but is this necessarily so for fibromyalgia? I don't think so. Also there are studies where they stimulate release of thyroid humans. There are literally hundreds of highly relevant studies here.
c) Aren't there things like thyroid receptor abnormalities that have different biochemistry but similar presentation to hypothyroidism? (And wildly different to fibromyalgia?) One has to look into this.
d) usually it's just tiredness and slowness isn't it? The fact that hypothyroidism presents so generally actually makes it less likely, not more likely to bear a specific connection here.
e) people with fibromyalgia often recoil if you try to examine them, take blood etc in a trait that they largely share with people who are anxious or have mental health issues with psychosomatic complaints.
What is needed here are similarities that are specific to these conditions and that are shared, whereas here it is the aspects that are the most general that are shared but the main facets of each condition are quite different and overall the two conditions don't blur together in an interesting way.
At the fourth attempt, my doctor managed to get the local lab to test TSH,T3 and T4 simultaneously. He had to ring them up and ask them in person, apparently. It turns out that I've currently got TSH~2.5, and FT4,FT3 low-in-range. Given that that looks like central hypothyroidism, and that's under the influence of 1 grain/day of desiccated thyroid, we've decided we that we have no clue, and I'm carrying on messing around with random thyroid drugs aiming for relief of symptoms (which are all gone, but I keep having to up the dose to keep it so).
Basically Christ knows. If I'm not medically unique, there's something very funny going on.
Aren't you just taking thyroid hormones analogues (not T3/T4) that are - as expected - suppressing the pituitary production of TSH?
That's what I was expecting, but 2.5 isn't suppressed, it's actually quite high compared to the average for healthy people, (or at least normal, depending on what you think normal is). And roughly the same as it was at the start of all this. And both the free hormones look low. You'd think adding a fair bit of thyroid to a healthy system would have bumped up the free hormones and maybe lowered TSH to somewhere like the hyperthyroid range.
What's really weird is that I've tripled the dose of NDT since the last time I had blood drawn, and my TSH has gone up slightly in response. I thought I'd be seriously suppressing my own system by now.
It's possible that I've just developed a primary gland failure, but that's weird because there was no sign of it when I first showed severe symptoms.
Ok so your TSH is normal and your T3/T4 are low in the normal range because you've replaced them with some T1/T2. Every value is in the normal range. Problem?
It makes no sense at all to call it pituitary failure (central hypothyroidism) - that would imply low TSH. You could argue that it's successfully medicated peripheral hypothyroidism if anything, though that's a stretch.