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Thyroid UK
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200 mcg - 400 mcg T4 prescribed in the past?!?

Hello all,

Over the last couple of months I have tried T4 75 mcg and it made me more hypothyroid although my FT4 and TSH levels seemed fine, but my FT3 level was not even mid-range.

I then added some 12.5 mcg T3 and lowered T4 from 75 to 25 mcg upon endo's recommendation. On this I felt the worst I have ever felt in my life!

I then dropped T4 completely and in the matter of 7 weeks upped to 85-90 mcg T3. I had a mixture of my old hypo symptoms and a fast heart rate.

Then accidentally one evening I took another 30 mcg of T3 and from the next day onwards I was able to lower my dose to 30-35 mcg T3 per day. I was little hypo, however my resting heart rate was always in the 90s and I started getting hot flashes and sweating.

I lowered T3 to 15 mcg daily and got back on my initial dose of T4 - 75 mcg.

Then in the matter of 7 days I dropped T3 completely and went up to 100 mcg T4.

I felt fantastic on this dose, realized I had forgotten what it was like to feel normal again. My energy levels were superb, I would sense only 2-3 flutters a day (my main hypo symptom - thousands of ectopic heart beats all day long).

My blissful moment was shortlived however. It lasted me only for a week after which I began to get more and more hypo.

A week later I upped my dose to 125 mcg T4 and again - I was feeling fine for a week and then started getting hypo again: many skipped beats, achy all over, and falling asleep 3-4 times during the day, absolutely no energy.

Tried adding some 5 mcg T3 on top of 125 T4 - very bad decision, felt even worse.

Now I dropped the T3 and intend on upping T4.

Apparently, at least from what I've read, T4 doses that are too low to shut the thyroid completely down only downregulate its function and the person ends up being even more hypo than before starting T4. Adding T3 produces the same effect, alas...

I want to try some NDT however I want to give T4 a chance first but I am afraid that I won't reach a dose that will heal me.

My FT3 is mid-range now, and I feel best with an FT3 on top of the range.

I am beginning to think that there is no chance for me to ever get better and I will be hypo in the next 5-10 years and then die of hypothyroidism affecting my organs and systems.

I have Hashimoto's, no TT, went gluten-free a week ago.

Is it true that 200-400 mcg T4 doses were prescribed in the past?

If so, why almost nobody tries it nowadays?

P.S. I am now convinced that I process even T4 very quickly. When I start/stop taking it, I can tell the difference right away, don't have to wait for 7-10 days.

5 Replies

Oh dear! You are upping and downing and swopping and changing far too fast. You're not giving anything a chance to work.

It's difficult to know anything for sure, but it sounds like, in the beginning, on 75 mcg levo, you weren't converting very well. So, it was a good idea to add in some T3. But, you might have been better off on a quarter tablet, rather than a half. And your endo reduced your levo by too much. 25 mcg would have been ample.

And the rest is just a mess, I'm afraid. Levo should be increased or decreased by 25 mcg every six weeks. T3 by 1/4 grain every two weeks until you get to one tablet, then hold for six weeks and test.

So, whatever dose of levo you're on now, the best thing would be to keep to that dose for six weeks, and then test to see where you are. Post your results on here, and that will give us a better idea of where you are, and what you should do next. :)

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The thing is I tried to hold to one and the same dose of Levo for 6 weeks and I was as good as dead. It seems to me that more harm is being done by being on one dose and not increasing it for 6 weeks.

I don't want to try T3 for the time being. Added to T4 it really makes me more hypo.

On the other hand I am afraid of rT3 built-up.


You will only make excessive rT3 if you are taking more T4 than you can convert to T3.

The point of waiting for 6 weeks is that it takes that amount of time for all the T4 to be absorbed and converted. If you increase before that time, you risk missing your sweet spot and over-dosing, which will set back your progress considerably. That way, you do risk building up excessive rT3, because the body doesn't like a lot of unconverted T4 hanging around.


In the past people were dosed on symptoms, not blood tests. I also suspect that many people were diagnosed much earlier than they are today. Perhaps those two things meant that people got more meds than they do now, because they could tolerate them better, because less damage had been done? I am just guessing.

We already know from people who post on the forum that many doctors nowadays prescribe 25mcg and think their job is over. And there are some idiots around who think that when TSH is in range they can take the patient off Levo because they are obviously cured.

These things are going to reduce the average dose. It doesn't mean it's right though!


Thank you, greygoose, humanbean!

I am afraid I cannot go 6 weeks without a dose increase. I have tried it more than once and it makes me even more hypo. I know that I have increased too fast out of impatience and sick feeling, but 6 weeks... ohh. I did not know that fast T4 increase leads to rT3 built-up.

How about those people who need a higher, over-range level of FT4 in order to deliver а suitable FT3 level?

Were people in the past put straight on 200 mcg T4? lol


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