Thyroid UK
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Mental tiredness and low mood - could adding T3 help?

I have never felt very well on T4 - mental tiredness and low mood being the worst symptoms. Does anyone know if taking a little T3 as well is likely to help with these symptoms? My doctor did say at my last apppointment that if I still didn't feel well, it might be worth considering T3 as T4 doesn't always suit everyone. Any advice would be much appreciated.

14 Replies

Nothing is going to work if you don't take enough of it. How much T4 are you taking? Has your doctor done the FT4 and FT3 to see if you're converting OK? Has he tested your nutrients to see if you have any deficiencies? Do you have Hashi's? All these things need to be taken into consideration before deciding that T4 doesn't work.

It's not a good idea to just jump into taking T3 without knowing your exact thyroid status. So, the essential tests that you need are :






vit D

vit B12



Only when you know the results of all these will you know if T3 is going to help you. And, if you post the results on here, with the ranges, people will be able to help you make a decision. :)


My dosage was increased to 100mg Levothyroxine but felt worse so now back down to 75mg and am also on HRT. I'm due to have more blood tests done in 2 weeks. Last results were:

TSH - 1.67 (0.3-5.0)

Free T3 - 4.6 (3.1-6.8)

Free T4 - 21 (12-22)

Vit B12 - 341 (200-960)

Ferritin - 62 (22-350)

Folate - 7.5 (3.0-18)

Serum electrolytes - creatinine - 87 (mildly raised)

Diabetes - 40 normal - no action

Calcium - normal

Coeliac - negative

Cortisol 355

Vit D 63

Yes have Hashi - can't find antibody result at the moment.


Well, not being able to tolerate a dose increase can be due to several things. It could be due to your low ferritin. Are you supplementing iron?

Your FT4 is quite high, but your FT3 isn't quite mid-range - too low - so, you will have a lot of unconverted T4 slopping round in your blood, which could cause problems.

So, a little T3 could help. But, you need to get the ferritin up first, or the T3 won't work for you, either. :)


Many thanks - that's really interesting! My doctor didn't mention there was a problem with my Ferritin levels so I'm not supplementing iron. What would you suggest I take?


Sorry, I don't know about iron supplements, I don't live in the UK. But, if you post a new question, asking just that, I'm sure a lot of people will reply. :)

Oh, and doctors know nothing about nutrition. For them, as long as something is in range, it's fine - and even when it's out of range, sometimes!


I do very well and quite fast on spa tone. Damn normal range is all Dr's look at. But it's so wide a range. I had to look back on old tears cos she did r even ask for ferritin. For goodness see . You'd think it would come up on a fbc or they'd know to order it for fatigue and aches. The amount of iron looks low but it natural and easily absorbed by the body... if you're in the UK then your d3 is really way too low. Optimal is 200. ..


Batchelor23 I had very good bloods on levo (t3/t4 in top quarter, tsh low in range) and felt awful. A bit of t3 (10mcg) has made me feel much better and the water weight I'd carried dropped right off. If I miss a dose I begin to bloat again. I'd deffo give it a try.


Thank you - I'm pleased to hear you find it helps. 😊


T3 was a god send when I first started adding it to my thyroxine, I had been taking 250mg T4 for seven years and still felt terrible, it was a light switch moment for me when I first added T3. Unfortunately it didnt last long, I think because I didnt know about all the vitamins, iron levels etc . I have tried various combinations of thyroid meds and have settled on Nature Throid and feel much better than I did.


From my experience, I'd say yes! Most definitely it is worth considering. Try it! Love that your doctor is considering it. It shows that he is aware you are not responding adequately to T4 only. For some, T3 is a miracle. It could be that you are not converting T4 into T3 as efficiently as needed for you to be optimal with your energy. When not getting enough T3 into your cells, fatigue, brain fog, low mood, depression (among other things) often result. Since your doctor will be following your progress, no worries. T3 is the active thyroid hormone of T4 (the inactive and stored hormone that is converted into T3 as we need it -- IF we can convert it!). While getting better on T3, you can try to research to discover why you are not converting T4 to enough T3 for you. Could be, as some have mentioned, your dose of T4 is too low. If your doctor recommended T3, I'd say s/he recognizes that T4 alone is not the answer for you. Glad you have a thinking and knowledgeable doctor!


Thank you for your response - you've given me some reassurance to give it a try if I get the opportunity. The doctor I saw has unfortunately now retired but I know it's all on my notes. She said it would need to be under the guidance of a specialist which I assume will mean another delay waiting for an appointment but hopefully it will be worthwhile. I'm due a blood test in a week which I will follow up with an appointment to discuss the T3 as I'm still not feeling any better but don't want to increase T4 again as it makes me feel worse!

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Glad to be of some small help to you!

Make sure you are getting all the vitamins necessary for optimal absorption of the thyroxine you now take. Sometimes, conversion issues can be caused by vitamin deficiencies. You take T4, which will be converted into the active thyroid hormone T3 -- but without the right vitamins in adequate supply in your body, that conversion cannot happen. When conversion doesn't happen as it should, T4 can make you feel poorly as it builds up in your body.

Here's a great link to read about the vitamins your body needs: hypothyroidmom(DOT COM)/10-nutrient-deficiencies-every-thyroid-patient-should-have-checked/

Healing Hugs!


Many thanks for your help! I exercise regularly and try to eat healthily but will certainly read the link and look into it a bit more. 😊

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I don't know the answer, but your question is a good one, I'm interested....for ANY solution to being tired, no getup n go, or enthusiasm for life...magic potion? Low mood, ya least you aren't alone with a low mood, I'm with ya....🐒


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