High TSH with high FT3 blood test with T3 only ... - Thyroid UK

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High TSH with high FT3 blood test with T3 only supplementation


I am hypothyroid and taking slow release T3 only supplementation for over four months now. My current dose, stable for more than a month, is 37.5 mcg twice a day (75 mcg total), morning and evening.

I have taken a blood test in the morning before my morning T3 dose. It shows a high FT3 of 7.7 (range 4.0 - 6.8), FT4 < 0.6 (virtually 0), but the most interesting part is that TSH is not suppressed, but is high at 4.3 (range 0.40 - 3.80).

I've been googling and only finding that when when either of FT3 or FT4 or both are high, then TSH should be down and in this case suppressed. So this is bizarre. Can anyone explain this? Perhaps it could give a clue to my condition and help me with treatment?

5 Replies

Less likely - a spike in FT3 from dosing, but since you took your T3 before testing that's probably not the answer.

More likely - you have in your blood antibodies that interfere with the TSH test giving a false high result. In some tests, biotin supplements can interfere. In which case, get another TSH done by a different method.

in reply to diogenes

No, I don't think it's a spike of FT3. I have been quite careful over the years about timing of blood tests. It's always morning, before 9 am, before taking any food, drink (except water) and any supplements/hormones.

To the second point, although false high TSH could be possible, but what I did not say in my post is that I am far from feeling optimal. My heart rate is still in the mid 50s with numerious hypo symptoms persisiting, but I was also getting anxiety and some other side effects.

I have been researching and I think the most likely thing is what Stop The Thyroid Madness author calls "FT3 pooling":


Basically, I think I actually need even more FT3, but my cells cannot absorb/utilise it. Hence, with lots of FT3 in the blood I'm getting some hyper symptoms yet with most of the hypo symptoms lingering.

What I have done since that test with my doctor is started on the hydrocortisone treatement. This was based on cortisol saliva testing being low. It has much improved my anxiety, but I have decreased my SR T3 from 37.5 mcg x 2 to 30 mcg x 2 per day. I can see that my hypo symptoms have become more severe and I'm stepping it back up to 35 mcg x 2.

My theory that I am testing is that hydrocortisone is improving FT3 utilisation and I can then slowly step up T3 to get the amount I need AND it being utilised by the cells. So perhaps the TSH indicator being ~4 is actually correct and I need to get into < 1 territory to feel well. This might happen at 40-50 mcg of SR T3 - a guess on my part.

The amount of T3 you are taking is supra-physiological - more than most people would need if they had no thyroid gland. This could be indicative of Impaired Sensitivity to Thyroid Hormone, also known as Thyroid Hormone Resistance. With this condition the body needs high Free T3 levels to overcome the resistance.

Your high TSH could indicate that your body needs even higher levels of T3.

With this condition a single daily dose of T3 (not slow release) normally works best.

in reply to HughH

Thank you. Please take a look at the reply to diogenes above.

.My slow release desiccated thyroid could no longer suppress my TSH during or after my low carb diet. Even with dose increase & very high ft3 it remained raised with heavy hypo symptoms. There has been progress this past 2 months ( it’s at 8 now ) despite no further changes in my dose over last 4 months aside from vitamins ect.

I had my Alkaline phosphatase (liver) tested and it’s very low .

Possible causes listed are anemia particularly related to low b12 / hypothyroidism/ malnutrition/ low calorie intake,/lack of sufficient protein/

Wilson’s disease being high concentrations of copper build up however the liver would be in stages of failure.

There’s no treatment for it other than addressing the underlying cause listed above according to main stream medicine.

Going to try stinging nettle as per NP doctors advice.

Why aren’t cells useing the ft3 in the blood stream/ I’d address vitamins,minerals , iron ect.ect. After that’s accomplished then it may take time for the body to change its previous patterns it developed during its deprived state & then cells ect will return to normal functioning /absorption.

A lot of things can go out of wack over time & it takes time & patience to rebalance.

Anyway I just thought you may be interested in the liver testing it wasn’t something I’d ever thought of being effected.

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