T4/T3 combo fine tuning - what would you do next? - Thyroid UK

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T4/T3 combo fine tuning - what would you do next?

Laundretta profile image

I've been self medicating t3/t4 combo for 8 weeks now. Previously was on 125 levo, dropped to 100 levo, added 6.25 t3, 2 weeks later went to 12.5 t3 for 2 weeks. For the last 4 weeks have been on 18.75 t3 (Plus the levo of course) I'm taking 12.5 early morning and 6.25 in the evening. The day before the blood test I took the 6.25 at 11pm. Tests taken at 9am. I've had no nasty side affects. I feel warmer. Skin and nails are better. I've lost a couple of pounds, although I'm not really overweight, just still a stone heavier than I was before all the thyroid shenanigans, so weight loss might happen if I tried harder. I'm trying not too change too much at once. However, I think I'm also now peri-menapausal, I've had a few hot flushes and irregular periods this year, but this started before the t3 was added. Just adds to the confusion, thanks life!

So my question is, do you think I should:

1. Stay on the current dose.

2. Add another 6.25 t3

3. Add the 25mcg levo back into the mix.

Bloods are:

(range then 125mcg levo / 100mcg levo/18.75 t3)

TSH (0.27-4.2) 0.297 / 0.024

FT4 (12-22) 20.1 / 17

FT3 (3.1-6.8) 4.27 / 5.35

Other current bloods are:

Active b12 (25.1-165) 161 (Thanks to injections)

Vit D 85.8 in June now 77.5, despite better You 3000 + k2 sub lingual spray. Will keep going with this.

Ferritin (13-150) 36.3 in June, now 64.5. I've taken Floradix over the last month. It has worked! I've bought a second bottle, even though it tastes like weeds. Urgh.

folate (2.91-50) Down from 17.03 to 8.89 since June. Don't know why as I'm still on the thorne basic b. Folate does fluctuate easily, I'll just keep on with the basic b.

Thanks in advance x

10 Replies

I think I'd leave any increase until autumn/winter, when it's colder. Your fT3 may rise in the meantime.

I take my whole dose in the morning, and don't sense any variation in fT3 through the day, apart from when I'm over-substituted and my upper arms can feel a bit shaky when chopping vegetables in the early evening.

Refused fT3 testing locally, I went by how I feel, with easier bowel movements, staying awake all day, and higher body temperature being factors. I had a test at a hospital appointment, with ft3 at 6.8 with upper limit of 6.5, but it was only five hours after my dose. Cutting my T3 slightly, I lost the noticeable benefits, but my fT3 had risen to 7.1 when tested six months later, in the summer. Cue another cut in dose and at least I've been comfortable when room temperature has risen above 23.5ºC. The longer term downsides of over-range fT3 for me may include "looser" shoulder and hip joints.

Thanks x

FT4 on 125mcg is 20.1,, this is quite high for a combo mix so I wouldn’t increase it anymore. I’m on 125/150 and my FT4 is only 14 (12-22). So your absorption is good.

I’d raise your T3 next as that’s where the wiggle room is. I didn’t introduce my slowly. Just took 15mcg in one day (3 spilt dose) after 10days I knew I wasn’t going to get on with the middle dose so I added it to my morning meds, so 10mcg morning and 5 at night. Then after my 6wk bloods I added another 5mcg to the evening. Then after 2wks I experimented with taking it all at once in the morning (20mcg tablets so then I’d not have to faff about cutting them). Also I was curious to see how I’d react because so many had said to be cautious and one needs it in split doses for it to be effective ect. I didn’t find any real differences, (I was also trying to see if it would help me to stop having vivid dreams - it didn’t) but as I wear a Apple Watch I could see that my heart rate had gone up from 63 RHR to 73 RHR so I switched back to my morning and night spilt dose.

I tell you all this to point out that we’re all so individual. I think we shouldn’t be afraid of experimenting. Just change one thing at a time so you know what works and what doesn’t.

Thinking about it, you may want to reduce your Levo when you introduce more T3 as that high FT4 score doesn’t seem to be converting into FT3 so what’s the point in it 🤷‍♀️.

Me personally I’d make those changes at the same time but others might advise you to reduce Levo, wait 6wks (personally is only want 7days) and then introduce more T3 but for me that’s just all too protracted.

Laundretta profile image
Laundretta in reply to NWA6

Thanks Paula. I’m also a RHR junkie. Mine was only 39 before I got diagnosed! It’s still only 53, but has gone up a little with each dose change. It was down a little over the middle t3 dose and I had some palpitations back. It’s a good barometer for me!

NWA6 profile image
NWA6 in reply to Laundretta

SNAP! lol I love looking at my RHR to guide me! Mine too was lollygagging in the 30’s and 40’s before I introduced T3, I’m also obsessed with my Heart Rate Variability. It was always so low before introduced T3 and now I can get it much higher!

I still need to get fit but it’s only been 3mrhs for me so I’ve been taking advantage and enjoying myself LOTS! Lol I’ll get fit in the Autumn 😬😂

Laundretta, Am I reading this right, you've been on five different doses in eight weeks? And in that time you've had two blood tests?

This is going at absolutely break neck speed, and the blood tests are only reliable if you stayed on that dose for 6 weeks before taking it.

I think probably my advice would be to stick on the current dose for 6-8 weeks or maybe more to give your body a chance to settle. See how you feel and then have a blood test. At the speed you've been going your symptoms won't have caught up to themselves yet, and you might find that you feel very different in a couple of months on this dose than the way you feel today.

I find that the first 2-4 weeks on a new dose can be very turbulent, and almost any strange thing can happen. For me it doesn't start settling down and giving me stable pulse and temperature results until after the 4 week mark.


Well, technically it is 4 doses in 8 weeks, however, I was following advice from seaside Susie for slowly introducing t3/t4 combination therapy having been on t4 only for 2 years. The first 2 t3 doses were only really intended as interim stations along the way.

I’d been on 125 levo for about 6 months when the first of the 2 blood tests quoted here was taken.

Then there was 2 weeks on 100/6.25, 2 weeks on 100/12.5 and 4 weeks on 100 levo and 18.75 t3. I felt pretty steady for at least 2 of those weeks before the 2nd blood test was done.

So I’m happy that the 2nd blood test is a reliable snapshot, I’m aware that the t3 blood levels vary due to its short half life and thus the 9am reading may be at the lower end of the daily cycle. I feel there may be room for more, but I find it useful to find out others experience to help me decide where to go next. So I may well just stick for a bit and see how I go. X

How do you get a test for T3. I’ve only ever been offered Levothroxine as treatment for my under active thyroid.


GP’s struggle to get t3 tested - usually the labs won’t do the test even if the GP requests it, unless your TSH is suppressed or your T4 is over range. If you can get your GP to refer you to an endocrinologist they will usually test t3. (make sure you’ve researched their specialities on your local nhs webpage and ask for the individual by name)

I have been through the process with a great Endo who increased my t4 dose. I also addressed nutritional deficiencies with the help of folk on this forum. Eventually the endo said I should have a trial of t3, but that current nhs rules mean I can only get it on a private prescription and I’d need to see him privately.

Instead I decided to get some Greek t3 and do it without the oversight of an Endo, but with the help of some googling and the experience of people on here. So I do my blood tests using a private lab (usually medichecks, sometimes blue horizon). You order and pay online, they post you a kit. You can pay a bit extra to get the blood drawn by a nurse locally or in your own home, or you can do a fingerprick. Then you pop it in the post and the results are emailed to you. Hope that helps? X

Thank you. I have been thinking about the medicheck tests. Maybe I will try it.

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