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Thyroid UK
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TSH below the minimum, but feeling good!

Last posted here about 4 months ago after having a full private blood test.

TSH 6.07 - (.027 - 4.2)

Free Thyroxine 17.2 (12.00 - 22.0)

T4 87.4 (59-154)

Vitamin D 61.5 (50 - 200)

My GP didn't accept the results so tested only TSH again

TSH 3.8 (.027 - 4.2)

No other reading recorded. I persuaded him to up the dose of Levo to 125mg to get the TSH lower. He agreed surprisingly.

Had blood done again this week after 3 months:

TSH 0.07 (.027 - 4.2)

Free T4 24.5 (9-26)

Free T3 4.9 (2.8 - 7.1)

These seem pretty good to me apart from the very low TSH level

I've been supplementing with 8000 D3 and K2 since December

Haven't heard back from the GP about the latest results, but I am wondering if he is going to want me to reduce the Levo back to 100mg which I was on before because of the low TSH.

I feeling pretty well at the moment with no contraindications of being overmedicated.

Also if the Vitamin D is making the big difference to the TSH level. I've certainly had less back ache and pains since starting the Vit D.

I seem to fluctuate like this from a TSH below .27 on 125mg and then up to 4 with 100mg. I suppose I could try 125 alternate days, but it's always a fag remembering which day I'm on. Pity there aren't 8 days in a week which would make it easy!

How do others do this?

So question is, should I resist it if the GP wants to change the dose back to 100mg? Also should I drop to 1000 for the Vit D supplements after the three months is up. Perhaps ought to get Vitamin D levels checked again to see where it is now.

Any advice gratefully received.

12 Replies

These numbers are OK if you are doing well. It's good to keep TSH above zero if you can, for various reasons. I would stay on this dose for another week or two to keep your recovery going. It's good to stay on the lowest dose that keeps you well, at least if your TSH is going very low. If you want to try alternate dosing you could take 100 mcg on Monday, Wednesday, Friday. You don't have to go alternate days with 100 / 125.

The only reason I might suggest keeping your TSH a touch higher is that if TSH is suppressed for a long time you get a 'down-regulated axis' and the pituitary produces less TSH. There is evidence this can reduce your T4 to T3 conversion. So if you can get away with a TSH that is not suppresssed that would be great but if you need the higher dose you have to go with it.

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Is this true if you have no thyroid as well?




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:

Prof Toft - article just published now saying T3 is likely essential for many, or we have to have high FT4 in order to get enough FT3.


Your FT3 is nowhere near top of range and FT4 is not over range either

All thyroid tests should be done as early as possible in morning and fasting and don't take Levo in the 24 hours prior to test, delay and take straight after. This gives highest TSH, lowest FT4 and most consistent results

Is this how you did test?

Be good idea to recheck vitamin D

Also what are B12, folate and ferritin levels like

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Thanks for you advice.

Last test was a fasting one, last Levo taken 24 hours before.

Vitamin levels when tested were

Active B12 73.2 (25.1-165)

Folate serum 8.32 (2.91 - 50)

Vitamin D 61.5 (50 - 200)

Been taking 8000 VitD capsules per day since November.


B12 is quite low. You may benefit from good vitamin B complex and/or B12 sublingual lozenges

If you are taking vitamin B complex, or any supplements containing biotin, remember to stop these 3-5 days before any blood tests, as biotin can falsely affect test results



Retest vitamin D soon

Vitamindtest.org.uk £28

Use a weekly pill dispenser - helps never to forget pills or what day it is!

Are you strictly gluten free? If not definitely worth trying


Thanks for the advice re B12.

I will loo into it.

I was going to retest Vit D at the end of the month as that would make 3 months of taking the high dose.

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Your TSH is fine. Don't allow your doctor to adjust your dose according to your TSH.

Pity they don't refer more often to the FT4 and FT3. Your FT3 could be higher so an increase in levo might be appropriate. I shall give you a link which explains in more detail about both Frees:



You've answered your own question as you say you feel 'Pretty Well'. So if it was me I'd be reluctant to reduce.

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These results show that you are a poor converter. And your FT3 is just exactly mid-range, whilst your FT4 is up the top of the range. Tell him that if he wants you to reduce your dose, you will need some T3 to replace it. It's low T3 that causes symptoms, and the TSH is pretty much irrelevant. You need a decent level of FT3 to be well.


Hi Zeph43,

I am new to this and still learning but just thought I'd let you know how I manage a regime involving taking different doses of levothyroxine on alternate days. On the first of each month i write on my calendar the dose i will be taking on the odd days of the month. Obviously the other dose is then taken on the even days of the month. This also makes it easy to check if I lose track. I don't know if this method would help you too. I hope so!

Glad you are feeling well at the moment. As regards your other questions, someone better qualified than I am will no doubt post advice.



Thanks for the suggestions Caroline.

Actually as you say it's easy to link the 25mg to the odd dates and 100mg to the even ones, assuming of course you know what the date is! Not such an issue when you are retired.


I am retired too so keep a small calendar and my pills close to my bed. It works for me. However if you can follow the advice of jimh111 that might be even easier for you. Hope all goes well at your next appointment with the GP anyway. Take care.


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