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Thyroid UK
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Thyroid T3 low


I have a few questions related to under active thyroid and high cortisol. My T3 is low 4.2 (range is 3.1-6.8) and gp recognised this fact.

My serum cortisol and salivary cortisol is high and I have read,I believe, on STTM that if cortisol and iron is not optimal then using T3 or NDT is not advised as you may feel hyper. I am having trouble with my gp who has referred me to a local endo on nhs who specialises in diabetes. I have asked to be referred to a thyroid endo outside of our health board, who believes in T3 and she has advised that this is only possible privately. I have already seen one privately for cortisol issues and his specialty was thyroid, however, although he knew i was hypo he didn't make the connection that high cortisol can interfere with T4 to T3 conversion so I don't feel inclined to see him again. Due to the cortisol issue I have, I am not confident in going it alone with either T3 or NDT.

Any advice please?

6 Replies


Hard to give advice without seeing what FT4 and TSH are too but increasing Levothyroxine dose will raise FT4 and FT3.

If you are able to tolerate Levothyroxine with low iron and high cortisol you will probably tolerate T3 or NDT too. You're unlikely to get T3 prescribed on NHS though as NHS England are trying to stop it being prescribed. NDT isn't licensed for UK use so is rarely prescribed on NHS.


Thank you for your reply Clutter. Here are my latest blood test results TSH 1.15 mU/L (0.27-4.20), FT4 18.6 pmol/L (11-25) 31st August In March this year when i complained about feeling severely tired and felt my cortisol levels were raised, GP did a thyroid test and results were TSH 0.17 mU/L and FT4 21.1(same range as August test), She then increased levo from .75 to 100.

I felt my system had gone haywire, through stress as 9 months earlier my mother passed away very suddenly and we were also told 3 months later that our dog was terminally ill.

GP wanted test repeated in 8 weeks so these were on 4th May, TSH 0.57 mU/L and FT4 18.5pmol/L

I realise I cannot get NDT/T3 prescribed but I thought if my cortisol was high then perhaps it would not be wise to take it. My ferritin and folate are both ok but I do not have the actual results for those. The lab refused to test Vit D as they said it wasn't practical/necessary? I hope this is more helpful Clutter as I discovered in 2011 that my T3 was 4.3, before all these events took place but I would add that I had two dysfunctional parents ( each in different ways) and I have been constantly suffering from chronic stress since the age of 5, hence the high cortisol which blood shows has decreased from 499 to 329pmol/L from 1st March this year to the present.

I have been feeling a lot worse energy wise/brain fog etc since May 2016 when my mother passed but I have recently started taking my levo at bedtime.

Thanks for taking the time to read my reply.



There is scope to increase Levothyroxine dose to raise FT4 and FT3 or you could try adding T3 to Levothyroxine to raise FT3, or switch to NDT. It is possible that high cortisol and low iron may make you feel hyper but it isn't a given that it will and if you are tolerating 100mcg Levothyroxine there's no reason why you shouldn't also tolerate the equivalent NDT dose.


Thank you for your excellent advice Clutter. I am pushing forward


GP may have said private only, due to the T3 friendly part, thinking NHS endo wont prescribe it now. However it should be possible to get refered to a thyroid specialist endo within NHS who has previously been T3 friendly (GP will know who has recommended it previously). Hopefully you would at least then get an honest opinion of whether it would benefit and willingness to monitor if self sourcing is the only option. If a good NHS endo is found they may do private too (and private T3 prescriptions) and at least you would be paying for good advice this time.


Thank you so much for your kind reply but NHS Wales insist on me staying within my local health board as they can provide an endo for me. The gentleman I wanted to see is only NHS otherwise I would have asked to be referred privately to him.What they don't seem to understand at my surgery is that an endo who specializes in diabetes knows nothing about the thyroid and it's complications. The local NHS endo doesn't practice privately, there is at least a 6 month waiting list to see him, but he could then refer me to the one I wanted to see originally! Another 6 months possibly wasted. I know a private endo who specializes in thyroid and have seen him already about my high cortisol. He wanted to look at my thyroid panel (TSH/FT4) and it didn't occur to him that the cortisol level could be what is causing my hypothyroidism including a low FT3. I have to admit I wasn't aware of FT3 and non conversion from FT$ then. However I am in the process of contacting another endo who practises privately and seems to have good reviews. Thanks once again.


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