Some discussion here about thyroid problems suggested a question.
How do autoimmune responses cause thyroid problems?  More specifically,
I can see how an autoimmune process could cause hypothyroidism -- the
immune system thinks the thyroid is foreign, attacks it, and voila, not
enough thyroid hormone -- but I can't see how an autoimmune process
would cause hyperthyroidism.  Is my guess about hypothyroidism correct,
and what's the story on hyperthyroidism as an autoimmune problem?
--
Daniel M. Rosenblum, Assistant Professor, Quantitative Studies Area,
   Graduate School of Management, Rutgers University (Newark Campus)

Actually, autoimmune disease can cause both hyper- and hypothyroidism.
The mechanism of hypothyroidism is more or less as suggested above: the
body presumably produces antibodies which cause inflammation and
eventual destruction of thyroid tissue.  The mechanism of autoimmune
hyperthyroidism (Graves Disease) is fairly interesting.  It's postulated
that the antibodies are directed against the thyroid recepetors for
TSH, thyroid stimulating hormone, but instead of causing destruction,
when the antibodies sit on the receptors, they act like the stimulating
hormone to turn on production of thyroid hormone.

--
David Rind

This is purely speculation on my part, but considering all the cases of
negative feedback loops that we've seen in endocrinological and neuro-
endocrinological systems, could it be possible that the auto-immune activity
is aimed in some way at a part of the negative loop (i.e. the receptor[s]
which downregulates the thyroid's activity).  Has this possibility been
examined?  It could also be a combination of these two processes (or, of
course simply the one that you describe).

Eric Zorrilla

What might cause an abnormally high concentration of TSH, but normal
levels of thyroid hormone? Should one be concerned about this condition??

This is sometimes seen in people with Hashimoto's thyroiditis, a type of
autoimmune thyroid inflammation, before they become hypothyroid.
Presumably, as the thyroid gland is damaged, increased amounts of TSH
are produced to cause the remaining parts of the thyroid to make
adequate amounts of thyroid hormone.  Anyone with a high TSH level
should be followed closely for the development of hypothyroidism.

--
David Rind

I haven't encountered this.  How high is the TSH?  Generally, if the TSH
goes very high due to a rare tumor, the thyroid will respond.  Hypothetically,
I suppose you could see this in the early stages of thyroid gland failure,
when the brain commands a bit more thyroid hormone than the gland is capable
of producing, despite it still being within the normal range.
I'd just have it checked again a bit later and see.

--
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Gordon Banks  N3JXP      | "I have given you an argument; I am not obliged

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Since you're discussing hashimotos disease I have a questions.  The
above description is what happend to me, finally my TSH got extreamly
high (140) and my thyroid hormone levels (t4) had dropped below normal.
I have been on the thyroid replacement hormone for almost 4 months and
I am still suffering some symptoms (although it is much better now).
I'm curious as to why I was not immediatly better once the thyroid
hormones were replace and the {*filter*} tests now show normal levels of
TSH and T4.  My Dr. says that the thyroid is still fluctuating and
it will take a while to settle down.  Another theory I heard from a
fellow patient is that your adrenal glands are effected when your
thyroid hormones fall below normal levels.  And not enough adrenlin
in your {*filter*} (or fluctuating levels) causes anxiety and distressed
feelings and possibly panic attacks.  My main symptom (although uncommon  
I understand) was panic attacks.  Any thoughts?  I would be interested
in finding out what exactly is going on.  Understanding the biological
process helps me cope.  Thanks