Feeling worse on NDT- should I change my dose? - Thyroid UK

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Feeling worse on NDT- should I change my dose?

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I’ve just started taking NDT - today is day 5. I was on 100mg T4 and 12.5mg T3 before starting on 2 grains of NP Thyroid (one when I wake up, one early avo).

I’m feeling awful- extremely tired, weak and my brain fog is much worse than usual.

I know starting dose for NDT would be 1 grain but my doctor thought it would be okay to start on 2.

Also taking iron, zinc and vitamin D. My B12 and folate levels are good.

Should I keep taking 2 grains and hope my symptoms ease or drop back to 1 grain? If I swap to 1 grain, how long should I wait to increase?

Any help much appreciated!

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13 Replies

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4 years ago

I didn’t- I finished T3/T4 one day and started NDT the next. Thanks for your advice

radd4 years ago

TiredPanda,

2 grains would contain more T4 & T3 than what you were previously medicating.

Don't forget that although 1 grain = 60/65mcg T4, it is bioequivalent to 100mcg T4 (as stated by manufacturers). Therefore, I think your dose is too high and you would feel better on 1.5 grains.

1 grain is not necessarily a starting dose as it depends on what you were medicating before. As you were already medicating some T3, doing a direct swop is fine.

Meanbeannyc• in reply toradd4 years ago

1 grain is 38mcg T4 and 9mcg T3. ***

radd• in reply toMeanbeannyc4 years ago

Meanbeannyc,

Correct 👏😀

Meanbeannyc• in reply toradd4 years ago

You wrote 60/65

radd• in reply toMeanbeannyc4 years ago

Meanbeannyc,

Oh sorry. That was because some NDT have 60mcg T4 and some 65mcg T4. I should have been clearer.

thyroiduk.org/if-you-are-hy...

Meanbeannyc• in reply toradd4 years ago

It’s 38mcg T4, it is not bio equivalent to 100mcg T4. 1 grain ndt is 38mcg T4 and 9mcg T3. It is equal to 38mcg T4 and 9mcg T3 because that’s what it is.

radd• in reply toMeanbeannyc4 years ago

Meanbeannyc,

Yes, you are absolutely correct in stating 1 grain contains 38mcg T4 and 9mcg T3, but remember T3 is more powerful so when added together is equivalent to 60mcg T4 (or 65mcg). Some NDT tables even have the '60' stamped on them.

However, because of the T3 contained in NDT, the amount of T3 converted from the T4 is considered more than if you were just to medicate T4 alone, so the manufacturers state in the PIL (patients information leaflet) 1 grain of NDT is ‘bioequivelent’ to 100mcg T4.

This can be confusing to understand but it is important to remember, so to reduce the risk of medicating too much NDT. The reason I mentioned it was it looks like the O/P's doctor has failed to consider this when dosing her, which is common with those unfamiliar with NDT.

Meanbeannyc• in reply toradd4 years ago

They label 1 grain 60mg, I do not know why. Considering the T4/T3 content is in mcg.

This amount of T3 does not equal that amount of T4. T3 has a 3-4x greater reducing factor on tsh than T4 does.

That’s where the equivalence factor comes in.

Yet 1 grain of ndt is still 38mcg T4 and 9mcg T3.

If taking synthroid and cytomel, it would be 38mcg Synthroid and 9mcg cytomel. This does not equal tbat

shaws4 years ago

1 grain of NDT is equal to approx 100mcg of levothyroxine. So 2 grains would be equal to 200mcg which might be a bit too much.

I am not medically qualified but I would suggest you start on 1 grain again and then after a couple of weeks you can add a 1/4 tablet every few weeks, always taking note of 'how you feel' and if your symptoms are being relieved. That is the aim i.e. feeling well again with no symptoms.

pennyannie4 years ago

Hey there again :

I think you should have started low and slow as detailed in my last reply to you :

NDT is not synthetic and I do not think you can do a like for like swop.

Since you had already taken T3 I think I'd have started on 1/2 grain and increase slowly and remember that the synthetic T4 will take around 6-8 weeks to fully leave your body.

• in reply topennyannie4 years ago

Hi PennyannieThanks so much- I’ve dropped back 1/2 grain in am and 1/2 grain in pm and feeling much better. Think you’re right- my dose was too high. Still yet for symptoms to disappear but have a while to go before that will happen I think!

pennyannie• in reply to4 years ago

Just remember the tortoise and the hare ??