Thyroid UK
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Pooling T3?

Hello everyone, i have been on NDT since April. I have two sets of blood results to run by you, taken at the end of June when on 2.5 grains of Thiroyd a day, and earlier this week having been on 2.25 grains since July 1st. On both occasions TSH was 0.03.

June: FT3 8.2 (2.8 - 7.1) FT4 14 (10 - 23)

Oct: FT3 5.9 (3.1 - 6.8) FT4 11 (12 - 22) I assume they have changed the ref ranges or lab between times.

I wonder if the T3 is 'pooling' to produce these numbers? I understand that this can be affected by iron levels, which were tested in June and here are the results:

TIBC 52 (45 - 81),

Transferrin % saturation 33 (15 - 45),

Serum iron 17 (6.6 - 30.4),

Serum Transferrin 2.3 (2 - 3.6),

Serum Ferritin 63 (not 67 as said earlier),

Haemoglobin 12.3 (low 12.5),

Haematocrit 0.35 (low 0.37).

GP did not repeat these tests this time. Also cortisol: last time it was checked (saliva test in April), my cortisol was too high and i take zinc and Holy Basil for this.

Or is it perhaps because i need to change to T4 only - Levo - and add in a lower dose of NDT for some extra T3? I understand there are sometimes problems with there being too much T3 in NDT for those who convert well.

In Aug 2015 I had raised Antithyroglobulin, and TPO in range - antibodies have not been checked since. My thyroid apparently is (otherwise) fine (according to the endo) no nodules etc

Thank you for any advice

9 Replies

Sorry, ignore the bracketed comment after the ferritin result - i don't have a reference range for this but i think optimal level is around 90 - 110 for women so i am below this


Your lab results re T3 look o.k. to me and bear in mind I'm not medically qualified.

I am not sure what you mean by 'pooling' and I take T3 only. If you are referring to RT3 go to March 24, 1999 to read the answer in the following link:

Others will respond re your other results.


Unfortunately this is an hrm page where content has gone. 😓


Hopefully, this will work but it is an 'archived' site as the doctor has now died.

1 like

Thank you that works.


I'm not sure what you mean by pooling, either. Nor why you think this might be the case. Your FT3 was a bit high in June, but it's rather good, now. But how do you feel?


Pooling is a term used on the STTM site. Here is a link where we can see that they say it is due to either low or high iron and/or low or high cortisol:

I had a bit more stamina when i was on 2.5 grains a day, but the GP wasn't happy with the high FT3 so advised me to reduce dose, which i did, down to 2.25 a day. Now i tend to feel a bit more tired and achey, and sometimes fall asleep in the evenings, which i wasn't doing on 2.5 a day. I will add that i have 60-90 mins of tennis lessons twice a week and play tennis league matches (doubles) so i am not struggling to function.

So, i felt better on 2.5 grains a day, but i don't want to potentially build up problems with too high FT3 later on, even though i wasn't having any symptoms of such at the time. :)


I am interested in this too as I have just had similar results which STTM say is pooling. I have high T3 and low T4 - but I don't understand the comments on the STTM below about the T4 as I thought that we can't convert T4 into T3 which is the whole reason for taking medication with T3 in it.

I wish this was easier to understand. My endo has just switched me to Thyroxin and T3 - I was on 1.5 gr of Armour but he won't support it. I am wondering whether to drop to a lower dose of T3 for a week and then build it up again.

Are you on the UK FB page for STTM - "FTPO - UK/Europe (For thyroid patients only)"? There is some good info on pooling Good luck getting an answer.


Yes i am on that group, it was probably my question that i asked a couple of days ago.

I think, depending on our thyroid problem and how much damage our thyroid has had, some of us CAN convert T4 to T3, we just aren't producing enough T4 in the first place hence the need for supplementation. My endo told me i didn't have a thyroid problem because i had no nodules etc, and just scraped into the normal ranges (last Dec) with blood tests, but since then they have agreed that i have a problem. My GP doesn't like me taking NDT but he can't make me stop and/or make me take Levo. We are our own best counsel on this i think, so research as much as you can and make your own decision on it :)


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