Thyroid UK
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T4/T3 dosing

Hi lovely people, hope you can help me un confuse my mind! Haven't posted in a while, just been trying to get through each day waiting for the next appointment, bloods etc.

I recently saw an nhs endo who has prescribed a 6mth trial of t3 (as well as the t4 I'm already on).

When I picked up the presc today I realised that not only has he dropped my t4 from 100mcg to 75mcg, he has also only prescribed 10 mcg t3 a day.

My recent bloods showed that my t4 is dropping (it was 18.2 previously) and that my t3 is low which means I'm not converting.

I am annoyed he has dropped my t4 as I felt like I could do with it being raised. I am also annoyed at the minute dose of t3. (Previously I was on armour thyroid, 2.5grains, so taking 24mcg t3 daily and still my t3 wasn't optimal.

I am tempted to continue on 100mcg t4 (as I have a repeat presc)

And take 20mcg t3 (split in to 2 daily doses).

Please can you advise me if my plan is a good one, I could well be missing some important info (like you need less t4 when taking t3?).

Or do you think I should go with what the endo has suggested? (75mcg t4, 10mcg t3 daily)?

I'm scared of feeling worse (due to less t4). This had been one hell of a year and all I want is to start feeling better.

Many thanks in advance


T4 17.4 (12-22)

T3 3.6 (3.10-6.80)

TSH 1.67 (0.27-4.2)

Fe 50 (13-150)

10 Replies

Chloe79, I don't think it was necessary to reduce Levothyroxine to 75mcg as your FT4 is only half way through range. I don't think your plan is excessive, you can always reduce T4 or T3 if you feel overmedicated. Your prescription will only last 3 months though so you'll have to buy online to top up.

Ferritin 50 is low. Halfway through range is optimal. Supplement Ferrous Fumarate and take each tablet with 500-1,000mg vitamin C to aid absorption and minimise constipation. Take iron 4 hours away from thyroid meds.

1 like

Hi and thanks for your reply. Yes I'm working on my iron and have managed to raise it from 27 to 50 recently so I'm happy to be getting somewhere.

I think I'm going to keep taking 100mcg t4. Last time I was on 75 I felt awful.

I am going to take their paltry 10mcg t3 and hopefully when my bloods still show low t3 in 6 wks they may raise it. I'm still attempting to get the nhs to pay for my meds but it's a slow and painful process that has kept me Ill far longer than I should have been.


Chloe, 10mcg T3 isn't a paltry dose, it's equivalent to 30mcg T4. When people are prescribed 20mcg they're usually advised on the forum to start at 10mcg for a week or two to see how they tolerate it before increasing.


Sorry! I didn't mean to sound so disdainful, just so frustrated at the mo with this all and so need to feel well again.

It's just tht when I was on armour I was taking equiv of 24mcg t3 and my levels were still low so I am feeling that 10mcg is going to make little difference at the mo to how I'm feeling. The pill is so small i can't even split dose with it so I will just have to take one dose about 4am with my Levo.


Chloe, buy a pillcutter and you'll cut the 20mcg easily. If you want to take 20mcg and will need to buy more T3 PM me for sources.


Can u recommend a good pill cutter? I did buy one but it just crumbled the pills.

I think I'm gna take the 10 mcg for at least 6 wks. Hopefully if my levels are still low they may agree to raise. This is a long journey just to feel well! Crazy.

If I fail I will be in touch for a t3 source. Thankyou


Chloe, I use a Pillmate cutter bought in a high street pharmacy. I line up the tablet score line with the vertical line on the pillcutter base and gently press down the lid/razor blade to cut the tablet.

It is a very slow journey. Rushing leads to overmedication which, in my opinion, is far more unpleasant than being undermedicated. Taking it slowly means you are less likely to overshoot the right dose for you.


Hi Chloe, I recently did the same and lowered my Levo 75mcg to 50mcg and added 12.3 mcg T3 split into two doses. This resulted in my already low FT4 of 5.1to 4.5, so now I am trying my original dose of 75 mcg and 12.5mcg T3. Will have bloods done at the end of October. Hope you find a good dose of each for you.


Have you found the t3 is helping you? I'm not going to lower my t4, hopefully I have enough to last till next bloods!! Thanks for your reply.


Did find the T3 helped soften skin and lifted my mood. Also helped anxiety. Had to lower it to 6.25 mcg yesterday as temperature rose to 37.3. So will revise situation over next few days. Suspect I might need more T3and less T4 eventually.

Chloe, a good pill cutter can be bought from Kleeneze. Only £2.99p.


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