Thyroid UK
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Levo's impact on natural T4 production ?

I recently realized from some discussions on other other posts that a Levo supplementation often causes the Thyroid gland to stop producing T4. This is something very interesting because it in turn means that once someone has gotten on to Levo, they can't roll it back because their body may not be producing any.

A significant part of my struggle has been contributed by my desire to keep supplementation to a minimum and let the body produce the balance, but it sounds as if I would be better off by stopping to expect the body to producce anything and just get as much supplementation as required to bring the TSH below 1.

That makes me wonder what would happen, if for some reason ( long travel or some unforeseen event ) a Levo dependant person did not get the supply for a few weeks.

It is SCARY to even think about.

Thoughts please.


8 Replies

While understanding the desire to take as little as possible, the target should and has to be right-dosing rather than minimum-dosing. We and the medics can discuss exactly what that means forever!

Intervention in hypothyrodism by throwing thyroid hormone at it may, in time, come to seem crude and even poor practice in those who do have a partially working thyroid. The problem is, we often do not understand exactly why such people become hypothyroid and so deciding how else to intervene isn't easy.

To take one specific but hypothetical example, if someone is unable to product TSH in their pituitary but has a working thyroid, then taking a TSH supplement might be a sensible approach. (This itself is a difficult approach - I suspect that TSH would have to be injected and probably could only work with an implanted dosing device.)

(Of course, for those without a thryoid, or with a largely atrophied thyroid, short of a transplant or similar, it will always be necessary to add thyroid hormones.)


Not taking levothyroxine (when needed) for weeks is a serious issue. Eventually (though in months or years rather than weeks) so-called myxoedema coma and death will result.

We all rely on other substances being available - water, food, other medicines - this is just another.

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…but at least we can go to the supermarket to buy water and food, there are no gatekeepers making it difficult to get what we need ;)

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On the other hand you can carry a year's supply of thyroid hormone in one hand! :-)

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Because thyroid hormones, if hypothyroid, keep our body working efficiently, if you stopped for several weeks it will put a huge strain on your body, i.e. particularly heart as well as everything else. That's why in the UK we don't pay for other medications because we have a very serious condition which could lead to myxedema coma if unmedicated.

We will not be given thyroid hormones unless we are clearly hypothyroid. It is a pity that the medical profession make some people wait till their TSH is 10 before prescribing and they would feel quite unwell. If hypo our thyroid gland is unable to produce sufficient for our body to function properly so we need supplementation.


Hi Sat77, yes I felt like you, that adding a little supplementation would be the best route, but it looks like that is not possible. I tried half a grain of NDT for a long time and ended up with lower levels of FT3 and FT4 than when I started although lots of symptoms had improved. Interestingly TSH was still well within range!

I had read all the info on supplementation stopping your own production but couldn't quite accept it, but it appears it is the case. I did ask the GP about this before I started self medicating and she didn't have a clue. I've had to learn through trial and error!


It may stop production whilst you're taking the Thyroid hormone replacement, but if you stop taking it, the gland will struggle to make as much as it can. It's a myth that once you start taking it your on it for life. Your gland just takes a rest because, goodness knows, it's probably been struggling for a long long time by the time you get treated.

Case in point : I was on T3 only two years ago (still am) but I stopped taking it in August 2013 (for reasons I won't go into). In March 2014, I noticed I was putting on a little weight, so I asked for my thyroid to be tested. TSH was about 35, and there was a little bit of FT4. Now I hadn't taken T4 for years, so it must have been my poor dying gland that had produced it. It still came up trumps even though it was on its last legs due to Hashi's.

Of course, it couldn't have kept me going much longer, but the point is, it hadn't packed up completely BECAUSE I'd been taking thyroid hormone replacement. I was taking thyroid hormone replacement because my gland couldn't cope anymore. Doctors always seem to confuse cause with effect. :)

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T4 is a storage hormone alone and it really does not matter if your thyroid stops producing it! Its the conversion to the working hormne T3 that counts.


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