Thyroid UK
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Lowering thyroxine

Hi everyone

I had my thyroid removed 2.5 years ago and have been on 100mg thyroxine since then.

I went to the doctor this week because of my excess sleeping and weight gain over the past 6 months. I have put on 3 stone (although I follow slimming world) and I’m sleeping around 12 hours on work days and 17 hours other days.

I just had a call to say they’re reducing my thyroxine to 75mg.

The receptionist didn’t have any more information so I’m going back to see the doctor on Friday. He only checked my TSH.

Does anyone have any advice on what other blood tests I should ask for?

Thank you!


6 Replies

Oh good grief, another doctor uneducated in treating hypothyroidism. Dosing by TSH when it's totally the wrong thing to take notice of.

TSH is a pituitary hormone, the pituitary checks to see if there is enough thyroid hormone, if not it sends a message to the thyroid to produce some. That message is TSH (Thyroid Stimulating Hormone). In this case TSH will be high. If there is enough hormone - and this happens if you take any replacement hormone - then there's no need for the pituitary to send the message to the thyroid so TSH remains low.

For proper interpretation we also need FT4 and FT3. T4 is the storage hormone which converts to T3 which is the active hormone every cell in our bodies need. These are the thyroid hormones and these are the important ones.

The aim of a treated hypo patient generally is for TSH to be 1 or below or wherever it needs to be for FT4 and FT3 to be in the upper part of their respective reference ranges when on Levo. See > Treatment Options

Dr Toft 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)."

Dr Anthony Toft is past president of the British Thyroid Association and leading endocrinologist.

You can obtain a copy of the article by emailing Dionne at print it and highlight question 6 to show your doctor. If you felt well on your previous dose, refuse to reduce with this article to support you.

If your GP says you must reduce, then say you want FT4 and FT3 tested first, and if FT3 is over range then you will reduce, but not otherwise.

By the way, the symptoms you describe scream "hypothyroid" and you are probably undermedicated - your FT4 and FT3 will show that.

If your GP cant or wont test FT4 and FT3, come back and we will point you in the direction of private labs that can provide them with a home fingerprick test for a reasonable charge.


Thank you so much for all that great information.

I’ll email Dionne now and I’m going to take a note of your points so I remember to say to the doctor.

He’s not the worst doctor I’ve had. One asked my why I felt the need to still be on thyroxine since it was 6 months since I had my TT!!

Thanks again.


One asked my why I felt the need to still be on thyroxine since it was 6 months since I had my TT!!

Ouch! So he doesn't understand exactly what the thyroid does and why having it removed might cause problems??? Beggars belief! I'd like to see how he gets on without his thyroid!

By the way, did you have thyroid cancer? If so then TSH should be kept suppressed to help prevent recoccurence.

1 like

I had a multi nodular goitre?

It had got so big even drinking water I had to swallow 3 or 4 times before it would move down my throat.

The operation wasn’t easy - there were problems getting the oxygen tube down my throat due to the size of it.

Lots of problems were relived but just seem to be replaced with new ones!


Also absolutely insist on testing of vitamin D, folate, ferritin and B12 as well as FT4 and FT3 before you will consider adjusting your dose

A GP is supposed to advise, not dictate

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

If you can't get full testing from GP ....

For full Thyroid evaluation you need TSH, FT4, TT4, FT3. Plus vitamin D, folate, ferritin and B12.

Essential to test, FT3 and FT4, plus vitamins

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. on Levothyroxine, don't take in the 24 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)

1 like

Thank you!! That’s great advice and I’ll definitely go for the paid test if my GP can’t do them. I just hope he listens to the results!

I had never thought about a GP advising and not dictating. That’s a great way to think. I’m really ready to argue my point now as I only work and sleep and that’s no quality of life.


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