Unable to maintain FT3 levels with NDT - Thyroid UK

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Unable to maintain FT3 levels with NDT


Could somebody please provide any insight to this perplexing and frustrating situation for me? I take NatureThroid NDT (5.5 grains) which has really improved my quality of life. I started with 3 grains around November 2015 and then built up to around 4-4.5 grains. I notice that when my FT3 is on the higher end of the range (5.3 and above where the range is 2.5-5.7 ), my hair loss stops almost completely and I feel great! TSH is always suppressed with NDT (mine is <0.01) and FT4 always hovers towards the lower end of the range (12/7- 13.7 with a range of 9-23 ). What should happen to the FT4 levels? I have had to increase the NDT from 4 to 4.5 to 5 to 5.5 over time after my miscarriage in order to maintain the FT3 level above 5.3 as it keeps dropping... Many thanks in advance

I had repeat bloods yesterday and my FT3 is now back down to 4.4 again after having been on 5.4 just a few months ago after my miscarriage when I increased to 5.5 grains.

Why is my FT3 level not maintained despite the fairly hefty dose of NDT?

Do I need to take T3 in addition to NDT to boost the FT3 level?

I am continuing to lose so much hair, which I know is always a sign of dropping FT3 levels for me..

What could be happening to affect my FT3?

I am loathe to increase NDT to 6 at this stage. I just feel there is a missing piece here, but have no idea to find out what it is..

Any advice v gratefully received.

A v happy weekend to all!

PS: I had a miscarriage in January, which may have affected my thyroid?

I am due an ultrasound of my thyroid in January.

Many thanks in advance

15 Replies

Too much thyroid hormone will make your hair fall out. Your dose is too high IMO.

It may be due to malabsorption. It would help greatly if you post your levels of Folate, Ferritin, B12 and D3 - those levels HAVE to be optimal or you will struggle to convert the necessary T3 no matter what.

Some reading on the topic





And last a really good post found earlier discussing proper supplementing due to commonly seen nutrional deficiencies - required reading IMO!


You may have R T 3 going on... (reverse T 3). This is where the thyroid medication you are taking isn't getting into your cells and it doesn't matter how much you take. As others have noted, you also need your iron, B 12 and D 3 checked and keep your fingers crossed that your adrenals are in good shape.

You may have to get a private blood test done to have your R T 3 tested and see if that is what is happening to you. The 'cure' is pretty simple. Drop NDT dosage to 1 - 1.5 grains per day with maybe a little T 3 added or - T 3 only. You do this for 6 - 8 weeks and then retest your R T 3. The R T 3 numbers should be normal or close to normal and you can start upping your NDT dosage again.

The condition will repeat if you fail to address what might have caused the R T 3 in the first place... low B 12, low iron etc... even undue stress.

Here is a website that explains it all much better than I.


Try chewing the NDT, put some of the paste under you tongue for a few minutes, I find I absorb it more by doing this. But back to fundamentals, do you have an absorption issue. Have you been tested for Coeliac disease. Coeliac's flattens your villi in your gut and you don't absorb stuff including NDT. Are you gluten and dairy free ? I would recommend at least gluten free for most people with thyroid issues.


An I just clarify a few points. Were you on Levo (T4) before you started on NDT? If so what problems, if any. Did you have then?

Are you taking the medication on an empty stomach and taking it with a full glass of water and then no food and drink other that water for a hour? I'm just wondering if you are taking it with food as that can affect absorption and may Bec ear other medication as that can Alter things as well. Clutching at draws a bit but just wanted to put a different slant on it as well.

As for the amount you are taking, I can only speak from my experience but I swapped over from taking Levo and got up to 3 grains, I felt better but not as good as I was expecting. -I had been on if for several years when I first started with a problem. But this corresponded with my bloods and seeing endo. I was slightly over range and he told me to drop back to 1.75 which I thought was a huge drop but he was right. I had gone passed my sweet spot and being over I'd very much like being under so I kept adding another quarter every few weeks. It's not always easy to tell.

Thanks so much to everyone for all your replies. I have been gluten free for 8 years now. was previously on Levo priro to my first miscarriage at 6 weeks. I continued after the miscariage, but felt like death with it so stopped completely. At around that stage my adrenals stopped working too, but have gradually recovered after I started the NDT. Ferritin has always been around 35 despite taking iron with Vit C as advised by this forum. I must have an absorption problem as my albumin never exceeds 32.. Taking NDT made me feel human again- I could barely stay awake before that, freezing cold etc etc. I have since had a 2nd miscarrige earlier this year, and have subsequntly been diagnosed with heterogenous MTHFR 6776 mutation. I then started taking B12 methycobalamin and Methylfolate and my ferritin has increased to 86 (but haemoglobin dropped to 10?). Vitamin D3 is now 80 so perfect (I supplment daily).

I understand about my gut issues but cannot understand why my FT3 levels remain elevated initially when I increase the dose but then drop again when I keep the dose the same?

I am totally exhausted of the constant health issues I have had to face. Thank goodness for this forum, which is the only reason I have managed to start healing myself..

Sincere thanks to everyone

hellybaybee in reply to Sangrom

I may be wrong but I thought D3 should be over 100 to feel benefit

Also what is your b12? Is it over 500 because you can feel symptomatic if it's below that

Also, what are you supplementing with? I take a prescription only version of d3 twice a week (I did take once but d3 was under 100 which I'm pretty sure is the magic number.) non prescription d3 may not be strong enough. Do you know the measure?

PS: I take the NDT an hour before, empty stomach, away from all other vitamins, iron etc and often also with some apple cider to increase absorption..

looselywoven in reply to Sangrom

Apple cider increases absorption? I hadn't heard that before. Thank you, I'm going to give it a try. x

A dose that is way too high will cause excessive amounts of Reverse T3 which will cause your free thyroid hormones to drop. Hair likes T4 on the higher end, I had a lot of hair loss before I went on T4 only, my hair is now staying put.

Please do some reading about Iron! Your ferritin is still low and not nearly optimal! This could be an important link and worth further examination.



FT3 varies SO much during the day that it is difficult to track a "level". If you take your medication and then measure your levels via a blood test you will find that your FT3 (or TT3 for that matter) is probably over range. If you wait until evening (on that same day) you will find that your T3's are minimal and probably close to the lower limit. You have to have a good history of blood tests taken at the same time of day under identical conditions to really make a conclusion about a T3 level.

I am full of beans first thing in the morning after my meds (NDT which gives me T3), I get 15 hours of normality then completely poop out about 8:30pm, I am fast asleep by 9:00pm - and it can all be controlled by T3 intake. Sometimes I take an extra T3 in the afternoon if I have to go out in the evening - but, you know, I am not sure that that is good practice.

Thanks so much to everyone for the very helpful comments- so much appreciated!

Hellybaybee I take 5000 of D3 per day. GP also gave me a prescription for the 20 000 which I took for 6 weeks.

LAHs I always measure the FT3 at the same time, first thing in the morning on an empty stomach, not having taken the NDT for 24 hours.

Rusty 64 thanks so much- will def work on the ferritin, although I always struggle to get that up..

Kalicocat thanks so much for the RT3 advice. I have read so many things on that. GP can't di Reverse T3 tests so I may need to pay privately..

One thing to ask you brilliant people:

I previously took Levo alone, and although my TSH went down as expected, my FT4 did not budge, and neither did my FT3 much and remained low.

I remained symptomatic and therefore took NDT, amnd immediately felt better. However while the FT3 (temporarily) goes up with NDT, the FT4 remains unchanged at 12-13 at a range of 9-23.

Why cano I not get my FT4 to go up either??

Any ideas v gratefully received

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