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Thyroid UK
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Which to reduce, T4 or T3?

Just got my latest results from Medichecks and it says I'm over on my FT3. I'm currently taking an evening dose of 100mcg T4, and a morning dose of 12.5mcg (half tablet) of T3.

Symptoms wise, I feel better with more T3 - much more energy etc. I have a little bit of chest tightness and a couple of other minor symptoms which can be ticked off the Thyroid UK hyperthyroid list, but nothing major.

What I would like advice on is whether I should reduce my T3 dose to a quarter of a tablet, or put my T4 dose back down to 75mcg. The added complication is that I'm going travelling for 6 months (seeing my doctor Friday!) so I need to make a decision quickly and haven't got too much time to titrate! Alternatively, do I try to take like 1/3 of the T3 tablet or some other dosage?

Results as follows (most recent first)

8/12/17 (24 hours since last 100mcg T4 dose, 8 hours since last 12.5mcg T3 dose)

TSH 0.105 (0.27 - 4.20)

FT4 17.4 (12.00 - 22.00)

FT3 7.64 (3.10 - 6.80)

4/9/17 (36 hours since last 100mcg T4 dose, 24 hours since last T3 dose (alternating 6.25/12.5)

TSH 1 (0.27 - 4.20)

FT4 13.6 (10.00 - 20.00)

22/6/17 (36 hours since last 100mcg T4 dose, 24 hours since last 6.25mcg T3 dose)

TSH 0.17 (0.27 - 4.20)

FT4 16.70 (12.00 - 22.00)

FT3 4.34 (3.1 - 6.8)

16/1/17 (24 hours since last 100mcg T4 dose, no T3)

TSH 0.19 (0.27 - 4.20)

FT4 19.35 (12.00 - 22.00)

FT3 5.87 (3.1 - 6.8)

23 Replies
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QueenMabroo,

How long did you leave between last T3 dose and blood draw?

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8 hours - I took my T3 before bed and drew the blood in the morning. I did it that way because my previous tests I'd left 24 hours and 36 hours, which I think gave me a false low.

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Queenmabroo,

Sorry, I just noticed you had said 8 hours. I think you are mildly overmedicated and would have said don't adjust dose except you are experiencing chest tightness. If you are able to cut the T3 tablet into 3 then taking 1/3rd will probably be fine. If you can't cut into thirds try reducing Levothyroxine to 75mcg/100mcg alternate days.

I hope you have a fabulous trip.

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Thank you! I think I'll try 1/3 tablet next, and chat to the docs Friday.

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If not had vitamin D, folate, ferritin and B12 tested recently I would get them redone and then re-evaluate

Have you seen this article by Prof Toft?

rcpe.ac.uk/sites/default/fi...

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I will ask the doc on Friday. Obviously, if any of them are low, then a supplement regime for that, but what would the knock on effect be to thyroid med levels? Ie would that suggest a reduction in T4 or T3 if they're out?

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Low vitamins stop thyroid hormones working

So you may not need to reduce

Are you on strictly gluten free diet

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Yep, strictly gluten free. I've never been told I had hashimotos, but did the antibodies tests with the last medichecks one. They're in range, though one's at the top end. I do have an old antibodies test where I think they messed up the ranges and that that one would show me to be hashimotos. So yes, I eat gluten free and don't have much soy either, though a little bit of dairy.

If it's low vitamins that stop the thyroid hormones working, would I not expect to see under range tests? Can low vitamins cause over range tests?

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when vitamins are too low blood tests show thyroid hormones are too high, but it's a false high.

Thyroid hormones struggle to be utilised so collect in blood.

We see this loads of times, especially after people have had T3 stopped, as this causes Vitamins to crash right out.

On T3 you might need higher level of vitamin supplements

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Ah, thank you! This was something I did not know. Great, I will talk to the doctor I'm seeing Friday - who is completely new to me!

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The concept of vitamins, gut function or gluten being anything to do with a thyroid condition will almost certainly be completely new (and unbelievable) to most GP's

You have been warned!

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So, she didn't do Vit D as I should be "supplementing anyway, particularly in winter, given my previous borderline level".

However, she did do B12, folate and ferritin. I think my folate and ferritin are on the low side but I can't remember the optimal parts of the ranges.

Serum vitamin B12 level 802 ng/L [211.0 - 911.0]

Serum ferritin level 81 ug/L [10.0 - 322.0]

Serum folate level 10.8 ug/L [5.4 - 24.0]

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Oh no, from checking my notes, B12 is now optimal, iron needs increasing, but I'm not sure what the folate range is?

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They all three look ok

Personally I would test vitaminD.

How much are you taking

Vitamindtest.org.uk £28 postal kit

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The betteryou 3000iu spray.

Thank you! I really appreciate the help.

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I don't think I have seen that Toft article, will go read now :) Thank you!

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12.5 mcg L-T3 is not a lot, reducing it might mean you get no benefit. I would try to split it into monring and evening doses, I find it quite easy to snap half talbets into two. Using a half life calculator your fT3 would be 6.8 after 12 hours (half way between doses?), so it isn't that high.

I would reduce your levothyroxine a touch, perhaps two days at 100 mcg and one day at 50 mcg (so you can just take half a 100 mcg tablet). This will allow you to continue with your current prescription and resume it if you feel worse.

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That's a possibility I hadn't considered, just splitting my 100mcg tablet on occasional days! That would save me from having the tablet fight with my doctor!

Should the test be done at 12 hours after the last T3 dose then?

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Best to take the blood half way between doses for the most accurate result. I appreciate some patients have to have the blood drawn earlier to fiddle the results so they can have a prescription but I would try hard to avoid this. It would be better to split the L-T3 into two doses and then have the blood taken a little after midday.

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May I ask why are you taking t3, you seem to convert t4 pretty well. I'm far from criticizing only asking for your reasons.

And what is the reason you want to reduce ether of the medication - is it because of chest tightness only or something else.

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I was not feeling well on T4 only, despite adequate vitamin and mineral replacement (my vits and mins need testing now, but before I started T3 in January I was good on those levels). Adding in the T3 has really helped me feel symptomatically better over the past year.

Mostly to do with the chest tightness, but also because of that medichecks T3 result (though I have also read that most places advise a retest before making a change).

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I understand T3 can rise if you have a virus and sometimes we aren't aware we have a problem but that I think is for a lower 'over range' than yours if that makes sense. May be better to retest leaving 12 hours after T3 and see if that is more acceptable.

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I am feeling a little bit virusy at the moment as well - throat a bit sore and sneezing.

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