Thyroid UK
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Dosing help please - Cynomel

Hello Gurus...

I received Cynomel ( T3) from France ... its says 0,025 mg !

I'm on 100 levo - doctor wont increase as TSH is marginally surpressed - I'm in bottom

40 % of range for T4 & T3 results ...

what dose of T3 should I take and how do I take it ( away from levo ? which I take at night ).

I'm feeling way better than afew months ago but my weight is just not shifting at all - I increased exercise to boost my metabolism but that seemed to make things worse !

any dosing help please for Cynomel gratefully received ...

9 Replies

0.025mg = 25mcg

1mg = 1000mcg so you just move the decimal point three places.

It sounds as though you want to use T3 for weight loss.

It was explained in your previous post last week

that with your current results

TSH 0.09 ( 0.27 - 4.2 )

T4 15.7 ( 12.0 - 22.0 )

T3 4.6 ( 3.1 - 6.8 )

that your FT4: FT3 ratio is 15.7 : 4.6 = 3.41 : 1

Good conversion takes place when FT4: FT3 ratio is 4:1 or less. Your conversion is very good.

Your FT4 is 37% through it's range.

Your FT3 is 40% through it's range.

Again, you can see your conversion is good as FT3 is higher in it's range than FT4 is in it's range.

You need an increase in Levo which will raise FT4 which in turn, because you are a good converter, will raise FT3.

And your reply was

"thanks so much for taking the time - so more T4 for me ..."

I think if you take T3 when it's obvious you don't need it you could cause yourself problems.

At the moment you don't have all your ducks in a row, a couple of weeks ago Clutter advised you that your Vit D, B12 and folate were low. You need to optimise these to get the most out of your thyroid hormone.

Vit D 56 ( 50-120) - needs to be 100-150,nmol/L

Serum Vit B12 263 ( 197 - 771) - needs to be very top of range, even 900-1000 for us Hypos

Serum folate 7.3 ( 3.9 - 25 ) - needs to be half way through it's range


Thanks SeasideSusie - My doctor won't up my Levo cause of surpressed TSH ( in fact it was all I could to not to get it reduced ) - I have started on all the supplements and will retest in a few months ...

A friend was returning from France and offered to get me T3 and I think I just got a little desperate and saw a way around of not being able to up my levo !!

My weight is a massive issue for me - I've gained 3 stone over 7 years - and just feel horribly unhealthy at this weight ... I love exercise but advice on here is that affects the T3 levels and could be making matters worse with my weight.

Feel a bit stuck ... thanks for great advice as ever and for taking the time

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If you have low FT3 then exercise may deplete T3. FT3 4.6 isn't low.

If you add T3 to your Levothyroxine dose you will also suppress TSH further. If you are adding T3 to raise FT3 I think that more than 1/2 tablet (12.5mcg) will push FT3 over range.


Thanks Clutter ... should I up my Levo do you think to raise my T3 levels ?

( I can try and source that privately too - or go back to Doc with a good case ) ...



Your TSH is mildly suppressed so I very much doubt your GP will increase Levothyroxine dose.


Have you considered that you don't have a sustainable source of T3? What are you going to do when it runs out?

I don't know how your friend obtained that Cynomel, but - speaking as someone who live in here - Cynomel is 'prescription only' in France.

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good point - hadn't thought it thru ... quite a funny storey about getting it ... a friend lives there part of the year and was telling her doctor that we cant get T3 here - she thought that was tosh and wrote a prescription FOR HER knowing it wasn't for her !!!!



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Improving your vitamins should improve your uptake of Levo and may raise your TSH a bit. Then Dr may be happy to increase dose of Levo.

Walking, yoga, swimming are good exercise, but not too demanding

Plus I see you only had a large dose increase 8 weeks ago. You need time to adjust.

Do you have Hashimoto's- high antibodies. If not been tested ask GP to do so

If you have Hashimoto's then trying gluten free diet is recommended. Very many of us find it really helps

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