Advice on Cytomel dosage please: Hi all, About... - Thyroid UK

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Advice on Cytomel dosage please


Hi all,

About two weeks ago I posted some questions but unfortunately I did not get a response. Maybe my post was too complex.

Since I still am confused, especially about my Cytomel dosage, would anyone please take a look and advise?

Tested Jan. 7, 2019 (private lab):

FT3 (2.63-5.71 pmol/L): 4.27

RT3 (0.14-0.54 nmol/L): 0.28

T3 (0.98-2.33 nmol/L): 1.22

Ratio T3/RT3 (> 6.00): 4.3

Tested Nov. 23, 2018 (hospital lab):

TSH (0.4-4 mU/l: <0.02

FT4 (10.0-24.0 pmol/l): 15.1

T3 (1.20-3.40 nmol/l): 1.79

I am confused that my T3 is pretty low and my FT3 is in the mid of the range. Does anyone know how this is possible and what is means?

Is Cytomel in the blood T3 or FT3?

Does anyone have any weird side effects of Cytomel? I mean side effects that are not the typical range of symptoms due to too low or too high dosage? I am asking because I have mainly hypo symptoms but am experiencing a new symptom that I would consider hyper. Since the increase of my Cytomel dosage in July 2018, I no longer have cold hands and I was very happy about that. But lately they are getting warmer and warmer, especially the fingers, and the skin of my fingers is extremely dry and coming off, making my fingers very sensitive and vulnerable. Creams/lotions do not do much. Would this possibly mean that my Cytomel/levo-ratio (20 mcg/0,15mg) is incorrect?

I would be very happy to read your thoughts on this. Thanks so much!


9 Replies

Your FT3 is 53.25% through the range, which is OK, although many people feel better with it about 75% of range, so if you are still symptomatic you could try a 5mcg increase in T3. It would be useful to see Free T4 and TSH and TPO and TG antibodies also, as you might need to decrease levo.

Thanks, Angel_of_the_North. I am seeing my endo only end of March to work out any changes, but it gives me a bit more peace to read your thought that I certainly am not over-medicated. I did not have my FT4 tested because it is below mid range for about 2 years now (also latest hospital test of Nov 23) and I had to pay the Jan 7 test myself. It is quite confronting to feel how hard it is to even consider trying to get an earlier appointment with the endo and ask for more tests... Happy to have you and all others here to share this with! Thanks!

The T3 test is actually a TT3 - Total T3 - because it tests for both Free T3 and Bound T3 (bound to a protein carrier). But it doesn't tell you how much of each, which is why it's a pretty useless test and why we need the FT3 tested. But, yes, it is possible for the FT3 to be higher than the TT3, and it doesn't mean anything.

There is no Cytomel in the blood. Cytomel is a brand name for synthetic T3. But, it would be Free T3, yes.

With an FT3 at mid-range, it's not surprising if you still have hypo symptoms. A lot of people need it higher than that. But, I don't think warm hands is a particularly hyper symptom. In any case, if you are hypo, you can't become hyper, the thyroid doesn't work like that. And, you're certainly not over-medicated with an FT3 at mid-range. Some hypos do have peeling skin.

There is no right or wrong ratio for T4/T3 when taking exogenous hormone. You need the amounts that are right for you as an individual. Some people, when taking T3, also need their FT4 quite high. Others do perfectly well with not T4 at all.

Forget the rT3 and rT3 ratio, they do not give you any useful information. :)

Jocelin in reply to greygoose

Hi Greygoose, thanks for taking time to reply so adequately and sharing your knowledge. It helps me a lot, to have your clarifying view on things. It sets me at ease and gives me more conviction which will help me in my future discussions with the endo. Thanks!

greygoose in reply to Jocelin

Glad to be of service. :)


Yes, it is possible to have higher FT3 levels than that of the free.

Not sure what dose of Levo you are medicating but in a previous post you advise of a split 20mcg T3 daily which is a good dose for many. Your FT3 is only just over half way through range but you don't have to necessarily increase T3 meds to increase FT3 levels, because by raising Levo dose you will receive that extra amount of converted T3 and a possible extra, should conversion improve with optimal medication.

In your previous post you had a load of tests. Your ferritin is low which can make thyroid hormone replacement hard to tolerate for some. You will need to supplement iron. Also there is no folate result (important as works together with Vit B12) or TPOAb result (thyroid antibodies).

Ask your doctor to test TBG (proteins that thyroid hormone is transported on) because high cortisol or oestrogen dominance (your oestradiol is greater than progesterone levels) can increase levels which could bind too much thyroid hormone so leaving too little "free" for use.

Also, elevated oestrogen can increase CBG (cortisol-binding globulin) which can leave too little free cortisol for use.

I don't know how long you were T3 deficient or how long you have been medicating it, but I consider when the body has been starved for years, it can take months for T3 to slowly locate and saturate each receptor, slowly and cumulatively waking up our bodies. After I added T3 to my Levo I initially felt huge improvements and then the rest took about 18 months. So I would say your warming hands could well be a result of the T3 as my cold hands were one of the last symptoms to go.

Jocelin in reply to radd

Hi radd,

Thanks for your extensive and helpful reply! You even looked at my previous post, which I appreciate very much.

Your thoughts are very interesting: it raises new questions. Would you please take a look and if possible for you, answer them?

You write 'should conversion improve with optimal medication'. Is conversion (co-)dependent on the measure of dosage correctness?

In that respect: Because of the pretty high rT3 I am afraid that adding levo would increase rT3 and adding Cytomel would not. On the other hand I prefer a slow release of hormones which would make levo more appropriate. I am now on 0,15 mg levo and 20 mcg Cytomel. What are your thoughts on this? I am asking because I have read that too much rT3 can also make you hypo.

Thanks for the ferritin/iron advice. I will get a good supplement for that. Can you explain or refer me to some website that explains the role of iron in the effectiveness of thyroid hormone replacement?

For the high estrogen I have bought just a couple of days ago these supplements that hopefully help lower it: vitex agnus castus and DIM.

If TBG is too high, what would be a solution? I assume that adding extra levo or Cytomel would have no effect because they cannot bind anyway? Or would they concur the estrogen away?

Very supporting to read how the effect of adding T3 was for you, especially with your hands. I myself do not know how long I am T3 deficient. I am taking Cytomel for I think approx. 3,5 years now. But most of this time I only took 5 mcg. Later it was raised to 10 and only last July after strongly demanding it from my endo, it was raised to 20. If saturation takes quite some time, it may still be in process than.

I know I have a lot of questions. I hope you will find time to get back to me. It would be of great help.

Thanks so much!



On page 134, Dr Peatfield explains in his book “Your Thyroid And How To Keep It Healthy” that for some patients the use of T4 alone doesn’t work (for whatever reason) and makes them feel unwell. He also says a long duration on this medication can cause more and more intolerances by inducing conversion blocks and receptor uptake insufficiencies, and the longer the patient remains on the intolerated medication, the worst the symptoms become.

It is generally recognised that adding T3 to T4 may suppress TSH levels that may induce a reduction in the rate of conversion but Dr Peatfield felt if the correct ratio of medicated T3/T4 could be met, this would not only compensate for the T3 loss but improve T4 conversion by clearing possible RT3 and encouraging better thyroid uptake. In his book he even claims some patients may be able to reduce their med dose after medicating T3 a while as everything works so much better. I experienced this and although now medicate NDT, I continue to function well on relatively low thyroid hormones compared to many on this forum.

Therefore, when medicating T4/T3, increasing T3 meds isn’t always necessary to increase T3 levels as it is also about achieving that correct T3/T4 ratio individual to us all. Because you continued to be symptomatic for many months/years after introducing 5mcg T3, it may be prudent to assume this wasn’t enough and your present dose of 20mcg T3 may be more realistic in you seeing some sort of recovery, and was the amount that I medicated together with 125mcg Levo. However, I had optimal iron and nutrients.

On page 137 Dr Peatfield states that once the patient is medicated correctly … [ … a change in status of the thyroid takes place and the pituitary control and thyroid response may improve, making T3 thyroid supplementation less necessary or sometimes even unnecessary altogether… ] This would only be applicable to those without a conversion impairment and I would not be brave enough to try it myself.

RT3 test results are notoriously difficult to interpret as are the result of multi factorial systems and symptoms will overlap with others such as high/low cortisol, etc. Optimising nutrients and iron and supplementing antioxidants such as milk thistle will help the liver clear RT3 from your body. Selenium is also thought to help.

Too much T3 can raise estradiol further and your true FT3 results could be higher than your test result is showing because you left 24 hours between medicating and the blood draw. Your TSH & Nov FT4 results allow room for a T4 increase but don’t forget increasing iron levels should eventually make meds work better anyway.

Vitex agnus castus I am not familiar with but DIM I have taken myself.

You will only know if TBG is elevated by having it tested. However, by balancing all other hormones, TBG should rebalance itself.


Treating RT3


Selenium lowers RT3


Iron helps Thyroid Hormones Work

Hi radd,

Thanks again! I have no words for the gratefulness I feel for what I am receiving from you. I have read your information a few times already, and will do so again to get an optimal understanding of it. I am impressed that you are able to so quickly provide me with such personalized extensive multi-faceted feedback. I go do my further homework :-).



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