Low FT3: Hi all, Hope everyone is ok and managing... - Thyroid UK

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Low FT3


Hi all,

Hope everyone is ok and managing to keep safe. At least now, with the vaccination programme well underway,the future is starting to look a little brighter isn’t it?

Anyway, I am posting in particular because I have just done a Medichecks thyroid check, the first since last August. I have been feeling fine apart from having to take a nap most afternoons. This doesn’t trouble me too much but I did wonder if I should just check my thyroid hormone levels.

My FT3 has always fluctuated between 4 and 5 but now is at an all-time low of 3.33. I don’t want to go down the T3 route - that seems too much hassle when most of my symptoms have resolved. However, I am concerned enough to wonder if I can up my dose of levothyroxine to advantage. I am considering increasing from 75 mcg daily to 4 x 75 mcg and 3 x 100 mcg, thus an average of 85.7 mcg daily. What do you think? As you can see from the attached my FT4 is already quite high. None of you will be surprised to know that the Medichecks Doctor was very happy with my results😳

I would be so grateful for any advice.

All the best


6 Replies

Wondering when you last tested your vitamins

Are you on strictly gluten free diet

Conversion is currently very poor

Have you recently had the vaccination (or Covid? )

Thanks, SlowDragon, for your reply.

I did have my vitamins checked at the same time and they were all very good. My ferritin was also very good at 135 ug/L (13 -150).

I have not been gluten-free for nearly a year now. I didn’t feel any benefit and my antibody levels have continued to fall steadily. Apart from tiring towards the end of the afternoon, I feel fine.

My only concern is my very low FT3. I had wondered if it could in any way be connected to the fact I had my first coronavirus shot the week before or the fact that I have recently been suffering from allergic rhinitis.

CRP HS was higher than usual at 2.32 mg/l (<5). Do you think it was the result of an immune reaction then? I did feel unwell during the evening following vaccination and had to go to bed, but I was fine the next day.

SlowDragonAdministrator in reply to Caroline888

You could try increasing levothyroxine. It might help or it might make conversion worse if Ft4 goes too high

I wonder if conversion of Ft4 to ft3 has got worse since you reintroduced gluten

Is rhinitis causing Post nasal drip .....suggests it could be dairy intolerance (dairy intolerance can develop if gluten intolerant and often improves on gluten free diet)

Thanks for that. Plenty to think about there!

The allergic rhinitis has subsided at the moment. It is not constant but recurs for a couple of weeks from time to time, perhaps twice a year. This last bout has eased considerably since we have been opening windows for 10 minutes each day. Indoor contamination is apparently a common problem in the winter months.

I’m not a big eater, particularly now when we can only get out for a daily walk with the dog, so I’m reluctant to limit my diet further at the moment, but I’m certainly going to look into the possibility that gluten is not helping with T4 to T3 conversion.

Thank you so much for your suggestions, you have been very helpful as usual.

Best wishes


You could do as you suggest and it might raise the T3 a bit - then see how you feel.

Caroline888 in reply to JAmanda

Thanks so much, JAmanda, for taking the trouble to reply.

Yes, I think I’ll do that and then get another blood test in a couple of months.

Thanks again.

Best wishes


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