Fine-tuning the dosage advice, please. - Thyroid UK

Thyroid UK
109,946 members127,798 posts

Fine-tuning the dosage advice, please.


I've posted results in the past and am grateful for all past advice and would like some feedback concerning the latest results of TSH, FT3, FT4.

My endo was suggesting that I lower the T3 dose I am taking because she didn't like that my TSH was slightly out of range. I insisted on keeping the T3 as is because it is only 5 mcg and I feel good on my present regime, where I did not feel good before adding T3. I asked her as an alternative that I lower the 75 levo I take, but she didn't want me to do that. We agreed that if I had heart palpitations to lower the T3. She has always been cautious about palpitations because I have been experiencing them for years. I noticed a reduction in that problem when adding T3 since last November.

Just to be safe, I am wondering if I should lower the T3 to half dose two days of the week so that it might keep the TSH in a better range? I look forward to any advice coming my way. Thank you!!

TSH, 0.19 mIU/L range: 0.40-4.50

FREE T3, 3.1 pg/mL range: 2.3-4.2

FREE T4, 1.4 ng/dL range: 0.8-1.8

26 Replies

She has always been cautious about palpitations because I have been experiencing them for years. I noticed a reduction in that problem when adding T3 since last November.

That would probably be because your palpitations were due to under-medicated hypo. They aren't always a symptom of over-medication. Far more often they're a symptom of hypo.

Just to be safe, I am wondering if I should lower the T3 to half dose two days of the week so that it might keep the TSH in a better range?

No, don't do that. It will undo all the good work the T3 has so far done. T3 has to be taken in a steady daily dose for it to 'work', you can't alternate with it like you can levo. And, you're on such a tiny dose. Your FT3 is only 42.11% through the range, so you're hardly over-medicated. And, your TSH is low because you don't need it anymore. It won't do you any harm. Trouble is, doctors in general don't know enough about thyroid to understand that. TSH is a chemical messenger from the pituitary to the thyroid, telling it to make more hormone. If you are taking more or less adequate exogenous hormone, the TSH is redundant. :)

Thank you so much for that helpful information! I will not lower the T3 dose, based on your advice. I would like to have your thoughts on what to do about the palpitations that I continue to have from time to time, even though they are far less than before T3. Thanks in advance.

If it were me, I'd try increasing the dose of T3. There's plenty of room for a 5 mcg increase.

Perhaps I will try an increase of T3 if palpitations persist. My endo is always afraid of Afib. so I don't want to disturb her too much since it took a long time to open her up to the T3. She is amazed that I am responding well to it. She's getting an education along with me. I tell her about this forum, hoping one day she will research it. There is always hope.

I think I will increase to 7.5 mcg of T3 and see the results.

Thank you once again!

You're welcome. :)

SlowDragonAdministrator in reply to saritadelmar

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, best not mentioned to GP or phlebotomist)

If/when also on T3, make sure to take last third or half of daily dose 8-12 hours prior to test, even if this means adjusting time or splitting of dose day before test

Is this how you do your tests?

Suggest you take the extra T3 as separate dose later in day, rather than as single larger dose

Also regularly retest vitamin D, folate, ferritin and B12

Canu in reply to SlowDragon

What about if you're taking NDT? When should you last take it before testing in the morning? (I was thinking that if you take it as one dose in the morning only, then by the next morning when you draw blood you won't have enough T3, but that if you split the dose and take the second one late afternoon, then the next morning you will hot have had a full 24-hour gap for the T4 to be correctly tested.)

8-12 hours for NDT as FT3 result is the most important.

SlowDragonAdministrator in reply to Canu

8-12 hours for NDT - the Ft3 is most important result. On NDT Ft4 is often low anyway

Thank you for the reminder of the dosing process the day before testing. I have been following your advice which you thankfully post periodically.

Following your suggestion, I will split the 5 mcg T3 in half for the day before the test, taking the second half 8 to 12 hours before the early morning testing.

If I increase to 7.5 mcg with a 2.5 dose of T3, I will take it in the afternoons. Normally I am taking 75 Levo and 5 T3 together each morning.

One question. If I increase T3 with an afternoon dose of 2.5, must it be taken every day, or can it be every other day to start? I would do the increase if palpitations return, as greygoose mentions an increase could help resolve them.

And yes, I am due for vitamin D, folate, ferritin, and B12 tests the next time around. Thanks again for your diligence and care!

Medics are paranoid about afib. I have it now. I was on 12.5mcg T3 and 100 Levo when I went into an episode and it just didn't stop. In the past my episodes would come and go about once every 10 months. They were awful violent things and could last for 2 days. But this? I hardly notice it. I have to take a beta blocker to keep the rate down, but the rest is OK. However, I stopped the T3 when it happened, having only just retested and my T3 had gone down since starting not up. It was nowhere near a problem level but still the medics blamed it. I stopped it and the Afib continued.

11 months later, in January of this year they gave me a cardioversion to put me back into sinus rhythm. It held for a while but I'm back in persistent Afib now. All that time I've had low T3 and now it's really low, in March this year it was less than 8% through the range and this week it's less than 16% through the range. T4 is about 2/3. I'm putting T3 back in. I can't stand to raise the T4 and I no longer think the heart doctors care what happens to me because there's nothing wrong with my heart, it's just the electrics that have gone wrong, so I'm going to do what I know makes sense. There are reports out there that say Afib can be caused by low T3. It's more often caused by high T3, but low is out there. I can't live like this, it's miserable and my GP doesn't care so it's going to have to be up to me. Don't let her stop your T3 and do go for an increase. Also, if you are female and 45 or older, you need to look at your reducing oestrogen levels with a view to replacing them too. That is a big cause of palpitations.

WOW, thank you for the reply, although much time has passed. I am having a phone conversation with my endo this coming week, and your reply has helped me stand my ground on the very low 5 mcg T3 I take. I'm on 75 Levo. I'm wondering if you have considered lowering your Levo while introducing T3 again?

My Endo resisted for over a year to give me T3 because she said that if it results in Afib, the chances of coming out of it are slim. But there are so many people with Afib that are not taking T3 so its a crapshoot. Meanwhile, I have fewer palpitations than before I took T3, so I can see/feel its effects. Immediately when taking the first dose my palpitations subsided.

I am well over 50 and of course, doctors say I am more susceptible to Afib. Again, with your recommendations, I am going to stand firm. My TSH was under range with my last blood work so I am thinking that if it is the same this time, I will have to fend her off with the statement, "I'm feeling well, so let's leave it alone." That's what I said last time. She is actually accommodating.

Any chance I can see your blood results? TSH, T4, and T3 at least.

A big thanks and please keep me informed of your progress, and the very best to you!


I have updated my Profile page to put the latest test results up for you. Mine is a long and hard journey, but the more I learn the better equipped I am for the next steps. You can see my TSH, FT4 and FT3 are all changing regularly whilst on the same dose of Levo. If you go back to November 2018 you will see I started on some T3 there and follow through to Feb/March 2019 when I came off it due to the Afib and doctors scaring me. You can see that my results were nothing like high enough to have caused Afib. I should have stayed on T3 and increased by 5mcg at that point but I was all over the place in my head. I've got used to Afib now. It's not as scary.

I don't intend to drop my T4 by 25mcg before adding in 6.25mcg of T3. I did that last time and my T3 level went down. I don't need that. My tablets are self-sourced 25mcg tablets so each quarter is 6.25.

Oh, and I will bring up the subject of estrogen replacement with the Endo as well. Thanks for the tip. Wishing you well!

On the subject of HRT,this may be of interest:

(Thyrotropin = TSH in case you are as confused by it as i was :) )

Thank you, I'll look at the link.

That has often been talked about , and it probably does have some merit, but that's a 19 year old report now and things in the world of HRT have changed tremendously in that time. Not least the preparations. Almost no one going onto HRT now would be given the old tablet form made from pregnant mare urine. It's now all body identical molecular structure synthesised from a base of yam plant. Almost all the modern oestrogens are from that new source and that makes a big difference. Most women will be recommended transdermal delivery methods now, patch, gel or spray, rather than tablets. It's worth noting that GP training in menopause is dreadful though, less than 1/2 a day if anything at all so they are the most likely to prescribe tablet form still. So you really have to do your homework with the modern menopause specialists and learn from them. A very good book from American oncologist Avrum Bluming called Oestrogen Matters is also a must read book.

You won't get successful thyroid replacement if your oestrogen is low. You might need slightly more thyroid medication to make up for the effects of HRT on Levo, but it's not a lot and worth the compensation.

Thank you for the added information about the HRT report. I think the transdermal method is the way to go. I have a friend that is doing that and it is working well for her.

I'll take a look at your profile page. It is always good for me to see what's going on with others, always remembering we are individuals with unique responses. I too got used to palpitations but was amazed at how a tiny bit of T3 gave a huge relief.

thank you for the update :)

I'm on Levo only , i've never tried T3, and i can't honestly say i know what people mean when they say palpitations, So please feel free to tell me to mind my own beeswax :)

But......... i can't see what your Endo is worried about. ;

The study i've read (Leese) shows risks for low TSH don't start until below 0.04, and there were no increased risks for TSH 0.04-0.4

This study is on T4 treated patients , but it's looking at risks of Low/High TSH

Your FT4/FT3 are both well within reference ranges.

These posts discuss risks of Low TSH

I've had a Tsh of about 0.05 for about 15yrs, i'm 54.

Have you ever tried NDT ?

Not yet . too skint just now ,need to grow my own pig :)

Or you could buy some from Thailand once air freight starts again.

Oh, good to know that the risk is at 0.04. I will be getting my new results this coming week and will take note of what it is now. But some say here to ignore the TSH, but gave no numbers as to when it would be a problem. Thanks for letting me know.

oops, only just noticed your post was a month ago. Silly me, not paying attention.

Glad it was useful anyway :)

It was much more than a month ago. I don't know why it is saying one month. But your reply is very timely while I prepare to speak with my endo on the phone this week.

You may also like...