Thyroid UK
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No longer able to convert T4 to T3

Hi everyone,

I'm waiting to be seen by Endo in Sheffield UK because of above. I'm suffering mega hypo symptoms despite being on 250 - 300 mcg of Levo each day (alternate dosage). GP unable to prescribe Liothyronine because of CCG decision and is suggesting I buy privately or travel overseas to purchase before specialist can see me but feel very unwell, struggling to stay awake etc. What can I do?

4 Replies

Can you add your most recent blood test results and ranges

For full Thyroid evaluation you need TSH, FT4, TT4, FT3 plus TPO and TG thyroid antibodies.

Plus very important to test vitamin D, folate, ferritin and B12

Low vitamins are extremely common and stop thyroid hormones working effectively

It's also absolutely essential to get vitamins optimal before adding T3

Many/most need to supplement to keep optimal

Private tests are available. Thousands on here forced to do this as NHS often refuses to test FT3 or antibodies

Medichecks Thyroid plus ultra vitamin or Blue Horizon Thyroid plus eleven are the most popular choice. DIY finger prick test or option to pay extra for private blood draw. Both companies often have money off offers.

All thyroid tests should ideally be done as early as possible in morning and fasting.

If on Levothyroxine, don't take in the 24 hours prior to test, and if on T3 don't take in 12 hours prior to test, delay and take straight after

This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, GP will be unaware)

As you have had Graves then you may find strictly gluten free diet helps too. I see you mention IBS on previous post

Dr Toft, past president of the British Thyroid Association and leading endocrinologist, states in Pulse Magazine,

"The appropriate dose of levothyroxine is that which restores euthyroidism and serum TSH to the lower part of the reference range - 0.2-0.5mU/l.

In this case, free thyroxine is likely to be in the upper part of its reference range or even slightly elevated – 18-22pmol/l.

Most patients will feel well in that circumstance. But some need a higher dose of levothyroxine to suppress serum TSH and then the serum-free T4 concentration will be elevated at around 24-28pmol/l.

This 'exogenous subclinical hyperthyroidism' is not dangerous as long as serum T3 is unequivocally normal – that is, serum total around T3 1.7nmol/l (reference range 1.0-2.2nmol/l)."

You can obtain a copy of the articles from Thyroid UK email print it and highlight question 6 to show your doctor

 please email Dionne at

Professor Toft recent article saying, T3 may be necessary for many. Note especially his comments on current inadequate treatment following thyroidectomy or RAI

1 like

Will pm you with T3 source so you can decide knowing timeframe ,cost etc


Hi Judith,

Any chance you could also PM me with T3 source?

Thanks DP


Hi Lynni,

It may be worth you being tested for DIO2 gene status with Genova Labs, that test can help identify conversion problems.

Best wishes DP


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