Thyroid UK

Dosing question: would appreciate input on this

I am curious if anyone else has experienced the same thing:

For a year and a half, I took 6 grains of Thyroid-S daily and felt great on it. Neither over-nor under medicated. This is what my labs looked like in August 2016:

TSH 0.01 (0.35-4.5)

FT4 0.9 ng/dL (ref 0.7-1.5)

FT3 2.9 pg/mL (ref 1.7-3.7)

FT4 levels on the low side, which is often the case when on NDT and supposedly does not matter if FT3 levels are optimal. Since I always wait 24 hours after taking NDT before going to the lab I could assume FT3 levels were about 20% higher on the previous day, so +/- 3.48. In other words: optimal FT3 levels, and that's how I felt. I was sure I had found my optimal dose of NDT, and was happy I had found an alternative available at a fraction of the cost of Erfa.

Then, in August this year, I went to another lab with different reference ranges...this is what my levels looked like two and a half months ago, on the same dose of Thyroid-S as last year:

TSH <0.01 (0.3-4.5)

FT4 18.76 pmol/L (ref 9.03-23.22)

FT3 8.48 pmol/L (ref 3.23-6.47)

So FT3 levels seriously out of range and FT4 levels above midrange...although I did not really feel hyper despite this, I decided to cut back from 6 to 5 grains daily. That was in early August, and I had new labs a week ago, so after almost three months on the new, lower dose of Thyroid-S. This is what my labs look like now:

TSH 0.01 (0.35-4.5)

FT4 1.2 ng/dL (0.7-1.5) so higher than on 6 grains a year ago (same lab so same ref ranges)

FT3 3.6 pg/mL (1.7-3.7) higher than on 6 grains a year ago

If FT3 levels were ca 20% higher on the following day, that means they were +/- 4.3 which is out of range. FT4 levels remain slightly above midrange despite going from 6 to 5 grains daily.

I have been considering lowering my dose further (to 4.5 grains daily)...the problem is that I am currently struggling with menopause so I have no idea what is causing profuse sweating both night and day.

What I am wondering is if anyone else has had to decrease NDT from a dose on which you previously felt good for a long period of time, and go down a grain or more...?

I know we supposedly need less thyroid hormone as we age, although I would not have expected it to happen so suddenly and drastically...

6 Replies
oldestnewest

On NDT I have experienced variation on blood results with different labs when one would expected more similarity. So your experience is familiar. Guess one should stay with same lab.

You seem to have non-thyroid issues going on which may be affecting need for your dosage. I am guy so maybe other might comment on this

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Thanks a lot! Yes, I agree it's a good idea to always use the same lab!

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Are you on any female hormones , i.e. HRT? This may well account for the change in levels.

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Yes, but I've been on them since 2011 (my hormone doctor prescribed them along with NDT). I have been on Oestrogel and Utrogestan; the first one I use day 5-25 of cycle, the second one from day 15-25. Interesting that HRT can affect thyroid hormone levels, I have never heard that...can you tell me in what way?

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If you have been on them since 2011 then I can't see them having an effect on levels so recently.

It's just that I know when taking a saliva cortisol test HRT does affect results as progesterone raises cortisol in the body. I just wondered if in turn they may affect thyroid levels. I've had a quick glance on the internet and from what I can gather, HRT lowers TSH which isn't what is happening in your case.

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True...thanks for the explanation!

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