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Thyroid UK
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Massive reduction in thyroxine dose

I have been on thyroxine since total thyroidectomy 3 years ago. I am usually on 100mcg but whenever I go on a diet and start to lose weight, my blood test suggests (and GP orders) a reduction to 75mcg. At which point the weight loss stops and reverses. Weight goes back up and I ultimately return to 100mcg thyroxine per day.

I have recently started a new diet, then was sent for annual blood test. GP's secretary phoned yesterday to say I must immediately reduce my dose to 25mcg. (75% reduction!!). I queried this (frankly I'm horrified) and have arranged to go in and speak to GP next week and get my results.

Can anyone tell me if this could be correct? I have been feeling fine on 100mcg. Should I do as I'm told until I see the GP, stay on 100mcg or reduce to a halfway point?


I finally got my results which were FT4 25.8 and TSH 0.09 (they didn't measure FT3)

I spoke to another GP at the same surgery over the phone and he has agreed to me to dropping 12.5mcg (alternating 100mcg/ 75mcg) which I am happier with. No-one has admitted that they made a mistake and no-one at any point actually asked about my symptoms or how I felt :-(

Thank you all for your replies and your support x

21 Replies

(((Tomella))) what a dreadfully unschooled GP you have. Regrettably in this regard you are not alone. The very fact of your increased weight the moment your T4 is reduced suggests that 100mcg is your sweet spot. So some things to ask before further advice: Was your blood test done prior to your levo dose that day, on an empty stomach and as early as possible in the morning? Do you have copies of these blood tests which have so alarmed your GP ? Are your vitamins all in a row and optimised ?

For the moment my sixpenn'orth would be to remain on your current dose and see what other information comes from other forum contributors. Just as an aside, 100mcg to 25mcg is a reduction which would only be advised by a medic of extreme ignorance of thyroid management and is positively deleterious to your wellbeing. Don't do it

*** I have no medical qualifications - simply a fellow sufferer ;)


Thanks for your reply Rapunzel, my blood test was done on an empty stomach (14hr fast) but I had taken my 100mcg thyroxine previously.

My GP is also questioning my Iron levels and wants a repeat full blood count.

I'll know more when I've spoken to her and got a full printout of the results.

I really don't want to reduce (let alone to 25mcg!!!) and felt I could safely stay at 100mcg until next week's appointment. Was just concerned that there could be something in my results that made the GP take such drastic action?


Then don't reduce. You know your own body because you're used to listening to it, whereas your GP is simply going by the blood tests. SeasideSusie 's given some great advice below.

Is your practice signed up for patient access yet ? You could see your blood results then, online, as soon as your GP can see them x


Taking Levothyroxine before your blood draw will probably have lowered your TSH. To get the highest possible TSH (needed when looking for an increase in dose or to avoid a reduction) you need to have left off Levo for 24 hours, fast overnight and book the earliest appointment of the morning. Your GP won't know this and probably won't agree.

Refuse a reduction until you've had a re-test, follow the above advice about testing conditions and ask for FT3 to be included.


Van you drink anything like lemon water. ? Trouble is that most the time im so drowsy on waking and once arrived for my test having fasted snd started to get naseous and low blood sugar levels thru the roof ad er all know thyroid controls metabolism. So i need at least some water and lemon to get me to the test. Anyone else experiencing this before?


Water isn't a problem, the advice always is to fast overnight but you can have water. I don't suppose squeezing some lemon into it will make much difference if any.


never bever never take your levothyroxine in the 24 hours before a test

that is the sole reason your test results are skewed

doctors fail to recognise this or tell patients

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never never never take levo in the 24 hours before a blood test or you land up in this predicament


Your body does not lie.basically if u feel good then why change anything. ? Going on a lower dose may spiral your balance out of control. But always best to get re tested for free t4 and free t3. As well as standard testing.

My symptoms get way way worse to the point im feeling like il go into a coma state when i take 0.05mg of eltroxin even tho ive been on it for 20 years. Today i decieded not to take it at all and im feeling way way beter. Stil a bit tired but the terrible ringing in my ears has subsided by 90% and im not half as anxious .

I started on mollases and cannibis oil to sleep is anyone here on cannabis oil. Im actualy a hoshi patient was diagnosed after taking thyroid meds for 20 years. All thanks to the gp.s out there who havnt a clue hoe we suffering and dragging ourselves thru life missing out on life most of the time and being labelled as losers when we are just plain sick .

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Tomella That is an utterly stupid suggestion from your GP. Reductions, like increases, should be in 25mcg steps. Just refuse to go any lower than 75mcg. But I wouldn't even agree to that unless you've seen your thyroid test results and seen whether your FT3 is over range. Chances are FT3 won't have been done so refuse the decrease until they do FT3 and only if it is over range agree to the reduction.

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 article by emailing louise.roberts@thyroiduk.org.uk , print out and highlight question 6 to show your GP.


I ditto Rapunzel. Though it would be interesting to see your test results [with their ranges] just to see why they want you to reduce.

I was going to post this up in a post of its own.

It's about how important it is to recognise clinical symptoms over and above the thyroid blood test... and for doctors to listen to their patients. "If you listen to a patient carefully the patient will tell you the diagnosis and if you listen even more carefully they will tell you the most appropriate treatment".

Rethinking the TSH Test: An Interview with David Derry, M.D., Ph.D. by Mary Shomon ''The History of Thyroid Testing, Why the TSH Test Needs to Be Abandoned, and the Return to Symptoms-Based Thyroid Diagnosis and Treatment''


And another one - An Interview with John Dommisse, MD ''Unique Theories About Hypothyroidism Treatment''



Firstly they can only advise, you can refuse to change dose.

You would need to see full tests FT3, FT4, TT4 and TSH before even considering it.

Also as others have said, tests should be as early as poss, fasting and no Levo for 24 hours before test

Also need to check vitamin D, folate, ferritin and B12 first as well

What about antibodies? Do you have Hashimotos?

If changing dose, even 25mcg is quite a large jump. At very most personally I would only reduce 12.5mcg (100/75 alternate days) but only if FT3 and/or FT4 were right at very top of, or over, range

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Thanks im so so grateful tonall the bloggers ive learnt more innthe last week ive discovered this blog then in 20 years living with thyroid meds !!!. Finaly dont feel like im the insane one in the lonely doctors rooms


You can't live on 25mcg Levo if you've had a thyroidectomy. You will end up in a coma.


I am guessing here, but I'm assuming that the reduction has been ordered because your TSH was suppressed when you were tested. You should remind your doctor that you have no thyroid and that having insufficient thyroid hormone could be a death sentence for you.

You should refuse to drop your levo dose.

You might find this post by helvella of interest.



if your fine on100mcg then thats your dose

its cdazy to keep messing with dosage and its unesecary and to reduce from 100 down to 25mcg would put you on a downward spiral that it will take months to recover from even once restored to 100mcg

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There is no way a person without a thyroid gland can survive on 25 mcg of T4 daily!!! That is only a fraction of what a healthy thyroid gland produces. As others have pointed out, you should decrease your dose gradually, by 25 mcg or even 12.5 mcg at a time. From what I can tell, there is no need for you to decrease your current dose at all. If you've had a TT, it's likely that 100 mcg of T4 daily is the minimum dose you require.

I have heard a lot about ignorant doctors over the years, but this is the by far the worst account I've ever read! I hope you can find another doctor with better knowledge of thyroid hormone replacement.

I agree you need to get a full thyroid panel asap, including both FT4 and FT3 levels. I have read many times that, if you've had your thyroid gland removed due to cancer, a very low (below range) TSH can reduce the risk of recurrence. So don't let any doctor tell you a TSH "anywhere in range" is good enough, and make sure your FTs are optimised...and that includes FT3!


Believe your body before a doctor! Go by how you feel not numbers.

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Here is another way of thinking about this: Stay on your 100 mcg, do your diet and lose weight. As you lose weight you will need less medication (there is a formula which expresses dose as a function of weight in KGs - if you are interested I will look it up), however, do not think about this until the 100mcg is causing slight hyper symptoms (fast pulse, jittery, mild palpitations). Only when you hit that point should you consider lowering your dose - by just a little bit - introduce 75mcg, but not every day, maybe every other day or just a couple of days a week, taking your 100 mcg the other days. Like Glynisrose says, believe your body before your doctor, go by how you feel, not the doc's numbers.

This process is opposite to our more usual problem of what you do when finding the correct dose, i.e. increase slightly until you feel well or get the jitters, then drop back a dose. You already feel good at 100, now you are going to drop the weight until you go slightly hyper.

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I looked up the formula:

Your dose of Levo in mcg = your weight in KGs x 1.7

Now, here are some doses for given weights:

wt in lbs wt in KGs dose of Levo in mcg

150---------------68 -------------------- 115.6

140-------------- 63 --------------------- 107

135---------------61 -------------------- 103

100---------------45.5 --------------------77

So if a decrease in dosage of 25mcg was suggested

this is equivalent to your dropping 40 lbs or about 18kg!

That's a great deal of weight, did you really do that? If not,

your doc is not calculating it right. OR... s/he is not aware

that you can drop by anything other than a standard dose -

that process is the same as "averaging down" i.e. if you take

100 mcg 4 days a week your effective dose is (4 x 100)/7

i.e. 57 mcgs per day and so on and so forth.

Hope this helps.

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Hi hun just read about the weight loss thing I'm currently on high dose levothyroxine but I have managed to loose four St in weight so guess that would affect my dose


That's great. The high dose of Levo is generating lots of T3 and that is causing you to lose weight. That's what happened to me, on 125 -137 mcg Levo my T3 was <100, when I bumped my Levo to 150mcg my T3 was >130 and at that point I began to lose weight - regardless of what I ate.


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