Thyroid UK
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Pooling on ndt

Looking for an explanation about pooling in easy to understand laymans terms. I am on 2 grains ndt, my FT4 is at the bottom of the range and my FT3 is just over mid range. rT3 is good and so is tsh. If ndt contains mostly T4, and mine is low, then I must be converting ok to T3? So is it T3 that I am pooling? Is that because of overmedication or is it adrenal/cortisol/iron issues? Trying to get to grips with this, and I thought I was doing so well!! Any advice/info welcome. Cheers x

13 Replies

These were my latest test results

TSH *0.051 mIU/L ( 0.270 -4.200)

FT4 *10.87 pmol/L (12.000 -22.000)

TT4 65.1 nmol/L (59.000 -154.000)

FT3 5.47 pmol/L ( 3.100 -6.800)

RT3 12 ng/dL (10.000 -24.000)

TGAb *241.900 IU/mL (0.000 -115.000)

TPO *132.7 IU/mL (0.000 -34.000)


Who told you you were pooling? Sounds to me more like you need an increase in dose, if you still have symptoms.

FT4 is low when you take NDT because the body doesn't hang on to as much. It doesn't need it, because you are taking T3 'ready made', so to speak. If the T4 were 'pooling', you'd have high FT4. But the fact that your FT4 is low, doesn't mean that you are converting it all. If you were, your FT3 would be higher. And, if the T3 were pooling, it would be higher than mid-range. I don't think you're 'pooling' at all. That's the way I see it, anyway.


Thanks greygoose, it is all very confusing. Two facebook groups I posted in both told me they thought I was pooling - very knowledgeable and helpful admin. I just need to understand it all a bit better - and the more people I ask the more confused I become!!


But why did they think you were pooling? What was the problem as you explained it to them?


If our thyroid hormones contain T3, our T4 will be lowered due to the T4. The blood tests were introduced along with levothyroxine so they cannot correlate if adding T3 or taking NDT.

The way to judge if you are on an optimum dose is by how you 'feel'. If not so good you may need an adjustment, either up or down. Blood tests are only a guide not a diagnosis.

Usually when you reach an optimum of NDT you feel better with no symptoms.

Some take up to 5 grains or even more (I am not suggesting you do this).

When you begin NDT, it is usual to begin on a starting dose, about 1/2 grain and then increase every 2 weeks by a small amount until you feel the benefit of NDT. If developing fast heart-rate or high temp you reduce to the previous dose and hopefully you'll feel better. I tried about 3 NDTs before I was happy with one.

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This is exactly what I did. Went up slowly to 2.5 grains, after a few weeks on that I started to get a few palps. So dropped back down to 2 grains a day and the palps stopped immediately. I feel good on the 2 grains. But according to what the other groups suggest I should drop my ndt to 1 grain and add in a bit of T3 - but really do not want to do this if it is not necessary - or if I have to do it I need to understand why. I have everything else under control (as much as possible anyway) - and was happy with the blood results when I saw them. Now I just do not know!!



How do you feel? If you feel well there is no need to make any changes.

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Clutter thankyou i feel good - I feel 2 grains per day is suiting me. 2.5 was obviously just a bit much. I think I will stay as I a for now and work on keeping my ducks afloat!!



How do you feel ? ? ...

"Pooling" is when we have a high "free" T3 result (showing we have a high amount in our blood stream) but are still symptomatic. This indicates the T3 is not getting into our cells to be activated and the reasons for this are various, and taking further NDT will just make T3 go even higher until the root cause is eliminated.

Excess T3 that is not being utilised can make you feel hyper and if medicating NDT, can eventually result in elevated RT3 as T4 will not be converted, as there is already enough T3 in the blood stream.

Low iron and cortisol are prime root causes but if you feel well , then stay as you are. Your results are fine as a lower T4 and TSH would be expected when medicating NDT.

You will only need to add extra T3 if RT3 raises but yours is fine and that gets complicated because if the further T3 doesn't alleviate the problem then pooling could increase ! ! ...

Better to work on low iron, cortisol and raised thyroid antibodies first.. especially if you are feeling ok.

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Radd that is exactly what I was looking for - a laymans description that I can understand. I think I will listen to you and clutter - work on everything else and retest in a few months. If rt3 starts to rise then I will have to rethink. Thankyou x

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You have very high antibodies.

How are you addressing that? Are you on gluten free diet? Or taking selenium?

Have you checked levels of Vit D, B12, folate and ferritin?


Yes thanks all that side is under control.


NDT is not mostly T4 you are thinking of levo which is T4 alone. There is a balance between T1, T2, T3 ,T4 and calcitonin.


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