Thyroid UK
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Should I worry about T3 being above range?

Hello. This is my first post although I have been following for months and have replied to others. Sorry it's a long read.

I have been taking self-sourced NDT (Thyroid-S) for 10 months and it has literally brought me back to life. This is the best I have felt in many years and all symptoms have been reversed.

However, my latest bloods suggest that I am over-medicated in terms of T3. Is this something to worry about? I am contemplating either switching to a combined synthetic T3/T4 regimen or reducing my NDT and supplementing with some synthetic T4. I am seeing my endo next Tuesday and, fortunately, I know he will be sympathetic to either of these approaches.

I'd be most grateful if you could look at the evolution of my dosage/bloods over the last months and let me know your thoughts. All bloods are via Medichecks and I have also tested negative for antibodies. Thanks in advance.

13/03/2017 - 0mg NDT

TSH 7.09 mIU/L (0.27 - 4.20)

FT4 14.14 pmol/L (12.00 - 22.00)

FT3 5.08 pmol/L (3.10 - 6.80)

13/03/2017 - 0mg NDT

TSH 6.76

FT4 14.5

FT3 5.3

26/04/2017 - 45mg NDT

TSH 4.88

FT4 12.6

FT3 5.7

I was feeling pretty rough at this point, I think because my endogenous T4 had reduced whilst my exogenous was still under-dosed, so that my overall FT4 was lowered as a result.

31/05/2017 - 90mg NDT

TSH 0.07

FT4 14.7

FT3 7.6

I was feeling good by this point but T3 is already out of range.

18/07/2017 - 75mg NDT

TSH 0.046

FT4 11.76

FT3 5.93

I was feeling rough again here. My endo had asked me to try 75mg for a few weeks but to come back up if it didn't work for me, which I did.

27/12/2017 - 120mg NDT Aug-Oct, 150mg Nov, 180mg Dec

TSH <0.005

FT4 21

FT3 12.4

This is the best I have felt. I have been experimenting with increasing my NDT and being wary of hyperthyroid symptoms such as palpitations, insomnia, but none experienced.

15 Replies

Just from my own very recent experience:

I'm apparently and seemingly "overmedicated" on t3.

T3 Bloods -> 10.7 (3.1 - 6.8)

Don't feel hyper or overdosed. Not planning to reduce dosage just to bring my levels to within lab ranges.

I'm going by symptoms. I feel good, don't feel the need to change it.

Having said that I may adjust the dose in the future but only if I get symptoms of either hypo or hyper.

Follow your gut instinct, I say.


Blood tests were invented for levothyroxine alone.

If we take other hormone replacements like NDT or T3/T4 or T3 only they cannot possibly correlate.

It is how 'we feel' that is the best indicator if the dose is optimal or not.

When NDT was invented our dose was increased until the patient felt well with no clinical symptoms. No blood tests at all.

This may be helpful:


Did you take your NDT on the day of the test?


No, I split my doses and took 60mg about 9h previously.



You are very overmedicated to have FT3 so high 9 hours after last dose. Having high FT3 increases the risk of developing atrial fibrillation so when my FT3 was over range I reduced dose.


Thanks for your responses so far. It seems to me that my FT4 has stayed pretty constant regardless of increased NDT dose until just recently when I have moved to a much higher dose. My FT4 is now at the top of the range and I do feel the best I have ever felt. I know that plenty of people feel their best when FT4 is around this level. So my question is really twofold: a) do I need to reduce my FT3? And b) how can I go about doing this whilst maintaining my FT4 where it is? It seems to me that NDT alone isn't going to work. Switch to combined T3/T4 synthetic regimen or reduce NDT and supplement with synth T4?

It's a shame that I wasn't able to get blood results when I was on 120mg NDT or 150mg but I just couldn't afford it.


I would suggest dropping your dose back down to 150mg NDT and monitor yourself carefully. Re-test in 6-8 weeks, if finances allow. If you don't feel any worse for dropping your dose, keep it there. If your health worsens, try an intermediate dose, 165mg, even if it means splitting a tablet. There's a lot of fine-tuning to be done at this stage.

Don't worry unduly about the raised FT3 at this stage, but it is something to consider carefully. There are people on the forum, myself included, who have peripheral insensitivity to thyroid hormone. This necessitates high doses of T3 or NDT, driving FT3 well above the reference range.

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When I started on NDT I got up to 3 grains but couldn't get any higher though t did feel better than on Levo. This corresponded with seeing Endo but I can't find my resultsat the moment but he told me to drop to 1.75 and much to my surprise he was right! To be honest I did feel a bit better in the way up! When we are learning then being over is very much the same feeling as being under so now when unsure I drop down and see how I feel to see if that is the way Togo.

I was told never to go over FT3 range on NDT though if it is a very small amount retestcin 3 weeks in case a virus had raised it.

When reading the results your TSH should be suppressed and your FT4 can reduce but your FT3 should never be above the range.

The only accurate reading is the FT3 so you can't tell whether you have a conversion problem as you need avid readings of FT4and FT3 to give you that.

I addressed this before I went over to NDT and have been pretty good since then but my vits hadn't been good so I spent 5 months improving them before I made the switch. All you can do now in that direction is test the Fab Four, Vit D, B12, folate and ferritin and supplement where needed. The time to improve them varies as to how deficient you are but it's well worth the effort. Plus high levels also help your general health and lingering symptoms.


Thank you. I also have these results:

Active B12 115.3 (25.10 - 165.00 pmol/l)

Folate (serum) 16.19 (2.91 - 50.00 ug/l)

25 OH Vit D 82.5 (50.00 - 200.00 nmol/l)

Ferritin 331 (30.00 - 400.00 ug/l)


but your FT3 should never be above the range

Except in case of peripheral insensitivity to thyroid hormone, which has a variety of causes, some of them genetic, some acquired. These circumstances are nowhere near as rare as endocrinologists would like to believe.

Sorry to keep banging this particular drum, but in my opinion some interpretations of blood tests results on this forum are over-literal and don't apply to all individuals.


Have a look at SeasideSusie's posts-very good info on vitamins etc


One thing to bear in mind is that if you have positive thyroid antibodies this will make your hormone levels fluctuate. Constantly trying to keep up with the fluctuations can be exhausting and frustrating, with one week having good results, another week being under-dosed, and the next week being over-dosed.

Do you know if you have Hashimoto's Thyroiditis aka autoimmune thyroid disease? You may find that you get no stability with your results until you can find the way to reduce your antibody levels.

Oh, and by the way... It isn't essential to have good levels of Free T4 when taking NDT unless you feel better that way. People taking T3 only often do absolutely fine with Free T4 levels of zero or not much above zero.

However, if you need Free T4 to be good in order to feel well then you might be better with NDT + Levo, or possibly Levo + T3. If you take a combo like that then you can obviously adjust the proportion of T4 and T3 you take to suit yourself.


Thanks for all the comments. My antibodies are normal and I think my vitamin levels look pretty good too.

I can only reiterate that I feel very well at the moment - better than I have for many years and no symptoms of hypo or hyper. However, I may try reducing to 150mg NDT for a couple of months and retest. And then, if I'm still feeling OK, I might go down to 120mg and see how I feel there. My gut feeling is that I have a problem with converting T4 to T3 and this is something I will discuss with my endo.


Did you remember to not take your medication before your blood Test


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