Hi I've been trying to look up on here what 20mcg T3 is equal to a 100 Levo I'm only adding in 5mcg t3 atm then I'll add it to 10mcg so I think I'm now taking 110mcg? It's only a trial period from my Endo Mercury Pharma t3 and t4
T4 T3 equivalent dose: Hi I've been trying to... - Thyroid UK
T4 T3 equivalent dose
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29 Replies
•
It doesn't work like that. There is nothing to be gained in trying to equate T3 and T4. We need what we need of each when on combo.
• in reply toLalatoot
Yes but how much thyroid meds am I taking when I add the 10 mcg T3 to my 100 t4 if I added more Levo t4 i understand the dose I'm actually taking sorry if I'm sounding confusing
Gsd2011
but how much thyroid meds am I taking when I add the 10 mcg T3 to my 100 t4
You are taking 100mcg T4 and 10mcg T3.
They are two different hormones, there is no real advantage in knowing what the equivalent is and it's impossible to say accurately what it would be, and there's no reason to know anyway.
T3 is said to be 3-4 times more "powerful" in it's effect than T4. So it could be that 10mcg T3 is roughly equivalent to 30-40mcg T4, but the way each individual uses T3 really makes it an unknown.
Can I ask why you want to know?
• in reply toSeasideSusie
Only because I'm new to it and want to understand how it works I was tempted to take 2 doses today one at 7am and one later today late afternoon but I've stuck with the 5mcg dose at 7am and Levo last night at 9.30 pm
Lalatoot• in reply to
You are taking 100mcg T4 and 10mcg T3. The hormones are different. You need to work out by trial and error how much of each you need separately. When on combo you are adjusting 2 different doses you can't count it as levo equivalent.
• in reply toLalatoot
The cutting in half is pretty easy but cutting again to get 5mcg is not never equal n crumbles a bit
Lalatoot• in reply to
You can get 5mcg and 10mcg tablets made by Morningside. However if you are not getting them via the NHS this will push the cost up.
• in reply toLalatoot
NHS Endo prescribed 20mcg tablet and said get a pill cutter and take 10mcg with the 100mcg Levo that's not too bad much easier if he prescribed 5 or 10mcg tablet oh well I'm surprised he even suggested T3
Lalatoot• in reply to
I'm lucky as my prescription says 5mcg x 2 daily then the GP surgery insists on giving me 5mcg tablets so I get a consistent dose. I thought they would have gone for the cheaper option and a pill cutter
• in reply toLalatoot
What times do you take your thyroid meds
Lalatoot• in reply to
6am 5mcg 3pm 2.5mcg 10pm 2.5mcgI have also done it as 6am 5mcg 10pm 5mcg. I haven't noticed a difference between the two methods
• in reply toLalatoot
Well I only had 5mcg so far at 7am still not sure how n when to dose with the 5mcg with 10 I can dose twice a day hopefully that might work
28 tablets 20mcg tablets is £101
28 tablets 5mcg = £98
So it’s extremely difficult to get 5mcg tablets prescribed
• in reply toSlowDragon
I can understand why he prescribed the 20mcg tablet Thank you for the info
T4 is basically a storage hormone, and doesn't do very much until it is converted into T3. So, saying is is X times more powerful than T3 is misleading, because it all depends on how well your body can convert that T4 into T3. It varies from person to person. And, my guess is that if you're taking T3 it's because you're a poor converter, so T3 is an awful lot more powerful than T4 in your particular body, but there is absolutely now way of calculating by exactly how much. Sorry if that reply is unsatisfactory, but that's the way it is. 
• in reply togreygoose
Hi There, no I'm not a bad converter the results lately tho t4 n T3 have gone down to previous results this year so Endo said try some T3 as I have felt awful for some time now I've been on 100 all this year and few months last year I could have added more t4 but Endo suggested T3 myself I would love to come off t4 only never felt good on it
greygoose• in reply to
OK But it still isn't possible to tell you exactly how much T3 is equivalent to how much T4. And, frankly, it doesn't really matter. All that matters is that you're on the right dose of both of them for you, and you feel well.
• in reply togreygoose
Early days greygoose it's just me getting it right
helvellaAdministrator
I recently tried to write a document to illustrate why simple conversion ratios simply cannot work.
dropbox.com/s/rhqk9059yld0s...
I hope it makes a little sense.
The worst thing to do seems to be to take a ratio, any ratio, and apply it as if it were true and accurate.
Remember, as soon as you change from levothyroxine-monotherapy, your body also changes. What might seem right on day 1 is very likely not to be a good predictor as you go on in time and, especially, if your doses change.
You have to combine how well you feel and Free T4 and Free T3 test results (if possible).
The concept of 20 mcg L-T3 being equivalent to 100 mcg L-T4 is false, an act of stupidity, it fails to take into account the relative absorption rates and half-lives of the tablets.
In the blood T3 has about 5x as much effect as T4. i.e. if you add 20 mcg T3 to the blood it will give the same result as 100 mcg T4 (when the body converts the T4 to T3).
In tablet form liothyronine is about 3x as potent as levothyroxine ncbi.nlm.nih.gov/pmc/articl... .
You have to take into account the 'pharmacokinetics', how well each tablet is absorbed and how long it stays in circulation. 20 mcg liothyronine equates to 60 mcg levothyroxine as measured by its effect on TSH.
• in reply tojimh111
Thank You this I quite a read not as simple as I thought
jimh111• in reply to
The equivalence is quite straightforward 10 mcg L-T3 equals 30 mcg L-T4. However, it gets complicated if a patient doesn't convert T4 to T3 as well as they should or they have a resistance to thyroid hormone. In these difficult cases they may need higher doses of T3 and T4 may simply not work. If you're confused just go by a 1:3 ratio. You are on low L-T3 doses so this ratio is reliable as a guide.
• in reply tojimh111
Thank You that's helpful
I've been down that road too. If I'm taking X amount of Levo and it's not enough Levo for my body then taking 10mcg of T3 isn't enough. For some people it may be. I don't know what your T4 levels in conjunction with your T3 levels are while on T4 only so it's hard to say why you felt poorly on levo. GPs seem to think if they give a thyroid patient Levo that the T4 levels should be the same as a healthy person.
• in reply tojrbarnes
Hi, I've always had pretty good t4 T3 results some times right at the top of the range but never felt good its only lately t4 T3 have dropped and a tsh for once in range I'm not sure why Endo suggested T3 instead of a increase in t4 but he knows I've not felt well on my better results either
SlowDragonAdministrator
Common to need to split T3 dose into 2 or 3 doses through the day
5mcg x 2 per day ….2nd dose approx 8-10 hours after first test
5mcg x 3 per day - doses approx 8 hours apart
Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and before eating or drinking anything other than water .
Last dose of Levothyroxine 24 hours prior to blood test. (taking delayed dose immediately after blood draw).
This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip)
Even if normally take T3 as single dose, day before test, split dose into three smaller doses roughly equal 8 hour intervals. Taking last dose T3 at roughly 8-12 hours before test
When were vitamin D, folate, ferritin and B12 last tested
shawsAdministrator
25mcg of T3 is approx equal to 100mcg of T4. I myself take liothyronine alone and I take one daily dose of 25mcg of T3.
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