Thyroid UK

T3 only - dose?

T3 only - dose?

Hi all last results below - I'm not taking T4 at all as Dr P said I wasn't converting- currently on T3 150 but still low temps, constipation, fatigue, sleep probs, weight gain, hair loss. I take T3 in 3 doses of 50 and NAX x 4, 3x1000 vit C, b12, vit D3 but struggle to manage iron tablets as need 4hrs either side of T3 I think?

Any suggestions very welcome please - thanks everyone

7 Replies

Monika53, 150mcg T3 looks like the right dose. TSH is low and FT3 almost top of range. FT4 is very low as expected on high dose T3.

Ferritin is very low, halfway through range is optimal. I can see it is difficult to take iron 4 hours away from T3 but you need some iron and low ferritin may be why you are fatigued so try it 2-3 hours away from T3. Take each tablet with 500mg-1,000mg vitamin C to aid absorption and minimise constipation. You might also try this

If you're using B12 sublingual lozenges or spray you don't need to take them away from T3. You should also take a B Complex vitamin to improve your folate and keep the other B vits balanced.


Thank you Clutter - this site is so helpful as my Gp is not interested and has told me repeatedly I need t4- could low ferritin also be causing the other symptoms ie weight gain as I started off really well on t3 but regained most of that weight in past 9 months- first time in 30 yrs I was beginning to lose some so 😞now!


Monika, I doubt low ferritin will cause weight gain but it does cause fatigue and hairloss.

You might try 100% gluten-free to see if it helps with constipation and weight gain. Several members have been able to lose weight and absorb nutrients better off gluten.

Having a conversion issue doesn't mean you can't take T4, it means you need T3+T4. I don't convert well and I can't tolerate T4 only but I prefer T4+T3 to T3 only. If you've been on T3 only a while and not feeling better it may be an idea to add in some T4 and reduce T3.

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If you don't convert, t4 can do you not much good, but keep you from raising the t3. Your dose is too low based on symptoms. At that dose and with those symptoms, you are thyroid hormone resistant, i have no doubt. For someone who isn't 35 t3 can put them over midrange on ft3. Also, you cannot go by labs on t3 only, just symptom relief. See if you can take it all at 1 time, like Dr. Lowe did with thyroid hormone resistant patients. You may still have to raise. Contact Shaws who is on this Forum and ask her for links to Dr. Lowe's treatment info. Yes, ferritin is low, but that is common when hypothyroid and may not come up until you are better medicated. Do you have anything wrong with your stomach which causes you not to absorb meds or Celiac or pernicious anemia?


Thanks Faith63 I'll have a look at Dr Lowe's info- don't think I have a gastric problem but GP not proactive or cooperative! I might trial higher dose after I've supplemented iron and see if that helps. Thanks again for taking the time to respond to me 😄



You can take the T3 first thing and then an hour later take the iron. You should have absorbed the T3 already and then after the iron you should have a few hours before the next dose of T3. (I was taking 3 doses of 50 T3, but now usually take 2 of 50 and add in 25 in the evening if I seem to need it, which is not often now).

I also had very low ferritin (17). I have now got it up to 69 at the last blood test (range 10 - 200) and feel much better.

My doctor was rather shocked to find that my ferritin was only 17 as I had been taking iron (ferrous fumarate EP 322mg) daily for years, so she doubled my dose of iron and that has helped. Since the last blood test I have taken my self down to the normal dose again, but you must check with the doctor, because iron can be poisonous!

Apart from being able to grow my hair, which is now much thicker (you can't see my scalp anymore!!) I found that I lost 7lbs in a week as soon as I started taking the extra dose of iron (it was water and I spent a lot of that week passing urine!). That has not gone back on, but with T4 I lost weight quickly (again only 7lbs) but since going on T3 only I haven't lost anything but palpitations and brain fog (which makes being 3 stone overweight bearable!). But I feel much better and my face looks like mine again, rather than the bloated moon face of before!

If you take the iron with vit C that can help with absorption and constipation - it certainly did when I took the effervescent C, but I had to stop after about a year, because it is high salt and my ankles were swelling. I found myself less lethargic with T3, and once you can move around more, constipation eases as well.

Good luck!


Thanks PiggySue- started today dosing with iron. Fed up with being told for years " if that's really what you eat - then you shouldn't be obese!!! " and endo suggesting gastric band or bypass if meds -and diet don't work. Ignored them all and saw Dr B PD instead and it worked at first so disappointed now . Researching now summer hols have just started. Thanks again 😄


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