Sunday, 10 August 2008

Hashimoto's Thyroiditis

Hashimoto's thyroiditis is one of the commonest causes of hypothyroidism in adults. It is an autoimmune disease where, for reasons that are still partially unclear, the body fires its arsenal at its own thyroid gland. The symptoms are largely those of hypothyroidism of any cause (e.g. fatigue, weight gain, bradycardia, slow-relaxing reflexes, etc.). Treatment is by replacement of T4 (levothyroxine), one of the two hormones produced by the thyroid gland.

Andrew Louis has asked a few questions about the disease which we'll go into one by one.

1. Why do we assess the success or failure of the treatment by measuring TSH levels? Why not T3 or T4?

With Hashimoto's thyroiditis, one has some residual thyroid function, just not enough to produce sufficient quantities of T4 and T3, which are therefore low. The level of TSH (which orders the thyroid to produce T4 and T3) will be higher than normal, which is fundamentally analogous to the body screaming at the thyroid to produce more hormones. This screaming does work a bit, as it forces what remains of the thyroid gland to work harder and make more of the thyroid hormones.

If you replace T4 a little, but not completely, you may end up with normal T4 levels - but only because the pituitary, via TSH, is still forcing the functional parts of the gland to work harder than normal. Only when T4 has been completely replaced will this screaming match stop, and the TSH will return to normal.

This is why TSH is a better measure of the success, or failure, of our treatment than T4.


2. Do patients benefit from T3 replacement?

In theory, giving T4 alone should be enough, since the body naturally converts some T4 to the more potent T3. However, some studies suggest that patients report feeling better, symptomatically, when given T3 together with their T4. More studies are needed on this at present, but it might be worth a try in some patients. However, taking T3 alone is not recommended, because T3 has a much shorter half-life than T4. This means that T3 would have to be taken 3-4 times per day and you would have to cope with levels of T3 that would fluctuate quite a lot (which can cause odd symptoms).


3. Can patients with Hashimoto's thyroiditis have normal TSHs and yet be symptomatic?

No, not for all intents and purposes. Autoimmune destruction of the gland will reduce its output of T4 and T3. This should stimulate the pituitary to produce more TSH than normal, as a way of signalling to the (remaining) thyroid to up its production levels.

However, it is possible to suffer from hypothyroidism despite normal TSH levels, although this is rare. It involves some sort of anterior pituitary pathology, whereby this gland is unable to produce enough TSH for that patient, even though the TSH is still within population norms. T4 will be low in this case, providing for an easy measurement. This is not, however, Hashimoto's thyroiditis.


4. Is there a benefit between the synthetic and the natural preparations of thyroid replacement hormones?

'Natural' preparations are made from the thyroid tissues of other animals. However, they are not recommended, as the quantity and potency of the thyroid hormones can vary greatly between batches. Anyway, 'synthetic' levothyroxine is identical to thyroxine, which is the natural version of this hormone made by your own thyroid gland.


5. Since Hashimoto's disease is chronic, why have a a lifetime of monitoring and dose changes? Why not simply remove the thyroid all together?

Alas, removing the gland wouldn't avoid a lifetime of monitoring and potential dose changes. In fact, a treatment for many cases of hyperthyroidism involves removing the gland (either surgically or with radioactive iodine), thus rendering these patients hypothyroid as a consequence. And as with Hashimoto's thyroiditis, such people also need lifelong monitoring to get their thyroid hormone levels right. However, once they are stable, levels only need checking annually, or even less frequently.

Removing the gland also has several disadvantages. For one, no surgical procedure is without risk, especially when operating in the dangerous neck area. Furthermore, since there is some functional thyroid tissue remaining, it is best to leave it in place. The reason that the average person doesn't need to measure their thyroid hormone levels annually is because the body will naturally adjust its levels to match the demands of the time. As much as possible, this function should be left intact, even if it needs a little artificial supplementation. Removing the thyroid in its entirety would make the levels even harder to control.


6. How do the adrenal glands (and cortisol) relate?

Usually they don't really. However, Hashimoto's thyroiditis is associated with other autoimmune diseases in a minority of cases. One of these is Addison's disease, which is chronic insufficiency of the adrenal cortex. (It has many causes; this is just one of them.) This would result in low cortisol levels (but there are many other causes of this biochemical phenomenon too!).


7. I hear there are advances on the way to cure auto-immune disease. Do you know anything about this?

Auto-immune diseases can be treated by:
  • Ignoring their cause and simply treating the symptoms - this is done in auto-immune thyroiditis and diabetes mellitus type 1, for instance. If you can get away with it safely, this is actually the best option.
  • Trying to suppress the immune system in general - this rather drastic approach is reserved as a last resort against debilitating illnesses, but its place is well-established if used judiciously.
  • Trying to modulate the immune system subtly - this newer approach is more promising, but amazingly difficult to get right. It can be done pharmacologically, or, even more recently, via gene therapy.

However, I'm not aware of any established and proven treatment options apart from replacing the missing thyroid hormones pharmacologically. The rest is either nonsense (as in some 'alternative' naturopathic remedies) or still being studied. However, I'm not an endocrinologist, so if you've heard of anything new, let me know and I'll look into it. :)

10 comments:

  1. How about this:
    Can a rate of decay be established?

    Consider the following labs:

    4/20/07, TSH-19.76,
    4/24/07, TSH-19.03,
    FT4-1.0, 0.8-1.8 NG/DL
    T3Total-101, 80-190 ng/dL
    - 50mcg Synth
    5/22/07, TSH-11.40,
    - 75mcg synth
    6/25/07, TSH-5.11,
    - 100mcg synth
    8/30/07, TSH-3.13,
    - "come back in a year"
    11/29/07, TSH-9.01
    12/6/07, TPO AB's - 590
    - 125mcg synth
    1/29/08, TSH - 0.46
    4/28/08, TSH - 1.38
    - "come back in a year"
    7/7/08, TSH - 2.81
    - alternating 125 to 150mcg synth

    1.) Is the above phenomenon a result of decay, or the result of not being at equalibrium with what's left of the functioning thyroid?
    2.) What is the max amount of medication necessary (I realize there's factor here) to sustain normal levels with no thyroid at all?
    3.) Is the level of medication relative to the function of the thyroid?

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  2. Hi Andrew,

    Thyroid hormones are potent customers that affect almost every organ in your body, including critical ones like your heart. The recommendation worldwide is to start cautiously and at a low dose initially, and work upwards gradually until the TSH level is appropriate. Starting with 50mcg is the usual first step - not because that's always enough, but because we want to start slowly. That seems to be exactly what was done in the case that you've given me.

    The eventual level of the medication IS related to the level of residual thyroid function, although it is also related to other factors. With NO residual function, most people are maintained on about 100-150mcg. However, this is only a population average; some people will require more and some less. The level that is right for you will be the lowest level that routinely keeps TSH within the lower normal range.

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  3. The above information if you do your research couldn't be more wrong!
    First off, I know from experience having Hashimotos and having normal TSH levels led me to just about pull my hair out and give up. This belief is exactly why ALL my doctors could not diagnose me. I had to beg my doctor to do an antibodies test that confirmed my belief.

    Next T4 is not the ideal treatment for hypothyroid cases or Hashimotos. There are many people that cannot convert the T4 Thyroxin sufficiently enough to feel well. This is why a T3 supplement is the ideal treatment.

    To make matters worse we have ranges that tell us "normal" and we conclude that with these levels there should not be symptoms. Find a doctor that treats based on symptoms and not numbers for Thyroid issues, especially Hashimotos and Hypothroidism

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  4. Hi anonymous,

    I'm afraid I stand by what I have written (it isn't a matter of personal opinions here either - the above is what the experts say).

    Re: your first point - I'm afraid that TSH levels should rise in Hashimoto's thyroiditis, and I explained the reason why this is so. It is exceptionally rare to have normal TSH levels - this implies simultaneous pituitary disease as well as thyroid disease, such that the pituitary isn't able to increase its TSH secretion.

    Furthermore, having thyroid antibodies in your blood does NOT indicate autoimmune thyroid disease! About 5 to 15% of women with NORMAL thyroid function have them (although these people are at increased risk to develop thyroid disease later in life.) If we were to diagnose Hashimoto's thyroiditis on the basis of thyroid antibodies, we would be giving potent medicines, with their own side-effects, to perfectly well people all the time. Again, the way to diagnose thyroid disease is with thyroid function tests. The usual one is TSH, but even in the highly rare scenario that I've just described, T4 would still be abnormally low.

    Re: your second point (on T4 vs T3). I was quite clear to outline the reasons for preferring T4 to T3, although I did say that some patients feel better if given T3 as well. Once again, T3 ALONE is not recommended (reasons above, again).

    Your final point, about normal values, is well taken, however. People do tend to regard laboratory cut-offs as absolute.

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  5. I have hashimoto's with my antibody levels aover two thousand and my ths levels have been completely normal the 3 years I've suffered with this, so I agree your wrong. I searched for three years trying to find doctors who would see how much pain I was in every single day, and 3 months ago they had to remove a tumor the size of a half of a baseball that was growing on my thyroid and tore my vocal cords. I had to research a specialist just tohave the antibody test taken, which was inconclusive for hashimoto's with normal ths levels, EVERY one is different. My doctor tells me it everday. One person may feel fine, the next is miserable for answers and to feel better. It's a constant battle.

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  6. I have been suffering from Hashimoto's for four years and STILL feel rotten! I'm tired of adjusting my meds every three months. I also have Celiac Disease so my Endo doc says that will be a constant issue for me. Now my PCH thinks my other physical issues are all in my head. How do you convince the medical field that WE know our bodies better than anyone...why do they not listen???
    Sandra (Arizona)

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  7. This information about normal TSH levels is indeed wrong. My father's throat had almost closed up, the doctor's thought he had throat cancer. It wasn't until a biopsy was performed that it was discovered he had Hashimotos, even though his TSH test was normal. Severe case, but the point is any information doesn't fit every person. People may have the same parts, but they don't work the same for every person. Any doctor will state that the heart isn't in the same location in every person, some people are allergic to different meds, etc. One size, or perhaps one statement does not fit all. Now as I watch my throat get bigger each year, as I feel pressure on my throat, as I cannot tolerate cold, have gained weight, as all my TSH still continue to be normal, as all of my siblings have Hashimotos, as did my father and all of his siblings, I'm afraid I too will have to wait until I cannot swallow before I am told what I already know...I too have Hashimotos disease.

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  8. Nope. TSH levels MUST be high in cases of hypothyroidism (including Hashimoto's), except in rare cases where there is a problem with the pituitary, as I pointed out above.

    The only way around this is if your labs have been using an incorrect maximum cut-off value for what they regard as "normal" TSH to be. In the past, quite high levels were used (8 or even 10 mU/L), but more recent studies have shown that the level should be more like 4.5-5 (and some authorities recommend an upper limit as low as 2.5).

    So if your TSH level is (say) 7.0, you may have been incorrectly told that this was normal (by older standards), when in fact it is actually high.

    This might explain why some people are still claiming that your TSH can be normal in Hashimoto's thyroiditis. It CAN'T. Seriously. But perhaps your labs (or your doctors) aren't using the right "normal" values as a comparison.

    Jeremy

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  9. Sandra have you looked into a gluten free diet to help your Hashimoto's symptoms and your Celiac's symptoms?

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  10. Jeremy,

    I agree that TSH must be high in cases of hypothyroidism; however, TSH is not always elevated in patients with Hashimoto's disease. Hashimoto's disease is an autoimmune disease in which the body produces antibodies against the thyroid gland. Only when the disease progresses to a point that thyroid function is impaired does TSH rise. I suggest anyone with questions that remain unanswered after consulting with their physician check out the Hashimoto's Thyroiditis article on the Mayo Clinic's webiste.

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