Thyroid UK

Help! T4 going down fast while T3 going up! Why? The Endo says no one knows why... really?

Hi All,

Thanks again everyone for your help and support with my previous queries. I am doing better than when I started on this journey, though I've gone through a couple of downs with a superficial blood clot forming on a finger and now the skin on my right hand knuckles drying, cracking and bleeding! But I've got lots of energy to take care of the little ones, cook, clean and remember to do most things needed during the day :-).

And here I am back with my third set of blood test results, the last one in the list below:

First set of results (Mar 5th)

TSH<0.01 (0.35 - 4.94)

Free T4 40.60 (9.01-19.05)

Free T3 34.80 (2.63 - 5.7)

Second set of results - (Apr 13th)


Free T4 12.3 (12-22)

Free T3 5.7 (I don't have the range but the Endo said it's in the middle of the range)

Third set of results - (Apr 23rd)

TSH<0.01 (0.35 - 4.94)

Free T4 10 (9.01-19.05)

Free T3 7.90 (2.63 - 5.7)

I was originally on 200mg PTU per day but reduced to half that as soon as the private Endo saw the second set of results. I was worried though it may be too much so I only took 100mg PTU for a week, and then 2 days before the second blood test I went down to 50mg PTU (my decision). The day I gave blood for the third time I was feeling very, very well, lots of energy, happy, active. Yesterday I saw the NHS endo who gave me the third set of results - so my T4 is very fast going down, and T3 is going up.

Is there any explanation for this, does anyone know at all?

The NHS endo did not have an answer, he is very happy with my results so he will see me in 4 months time with the next blood test results in 6 weeks time (and he also wanted me to stay on 200mg per day, he's got no idea the dosage has been reduced; there is no point in talking to him). But the private endo has requested another set of blood tests this week so I shall have blood tests more often.



9 Replies

You need to be on a stable dose for the blood test results to mean anything. I'm not sure why you are seeing two endos. You should stick with one, they can't both be responsible for your care - at the moment neither is. In hyperthyroidism the ratio of T3 to T4 released by the thyroid gland can vary. PTU also reduces T4 to T3 conversion, so by changing your dose you may cause short term variations in your fT3 levels. Consequently the recent blood test results are not much use and your NHS endo is placed in an impossible position as they have been misled about your dosage.

I'd suggest you think about which endo you want to go with in the long term and stick with one, being honest about what you are taking. As you have Graves' this could lead to eye problems in the long run (only a possibility) and so you will need continuing care. If on stable doses of medication your fT3, fT4 numbers continue to vary substantially they can introduce a regime of 'block and replace' whereby they block you thyroid action completely and prescribe levothyroxine.

I can't see the point of another blood test this week as your medication has changed recently. Maybe you could save yourself the cost by cancelling it and waiting for the test in six weeks time.


Thank you for your reply. I thought that maybe the dosage of PTU may have something to do with the T3 going up, of course I'll mention the change in dosage to my private Endo as I've always followed his recommendations. I got scared last week when suddenly the skin on my hands started tearing up and bleeding and I started to feel tired, very cold and having some memory trouble, so wondered if I was going hypo and had no one to talk to (private Endo on holiday) so made the decision to take less PTU just in case.

I am seeing two endos because the NHS care failed me in the beginning and they put me on the wrong medication while I was breastfeeding and they had only given me an appointment for April 20th as the first appointment. So in that situation I had to find someone fast as I had my diagnosis in the first week of March and that is why I went private.

I had tried to reach the NHS consultant by phone but no one called me back until a week later when I had already setup the private Endo appointment. When the NHS consultant realised what he had done with the medication immediately he brought my appointment forward just at the end of March, so I thought I would first see how the Endos compared to each other in their care towards me so I could choose the one that actually seemed interested in my well being.

So I've had my second appointment with the NHS consultant and he has no interest in seeing me earlier than 4 months or doing blood tests any sooner than 6 weeks, no interest in changing the dose of 200mg / day even though my T4 is borderline low, and all he talks about is how I am most definitely never going into permanent remission so they will have to put me through surgery!

The blood test this week is for the private endo whose advice I am following and he is going to be the one I am going to stick with, as he advised the right drug from the beginning, put me on the minimal risk dose for the baby and reacted by lowering the dose when my blood tests showed huge improvement in a short period of time.

I do not see why it would be bad to have more blood tests done (I pay taxes and I also pay for private insurance) - I do not want to go hypo and this is a way of monitoring it. I've got two little kids to take care of and I need to do everything in my power to make sure I am treated correctly. I've read some horror stories on this site and I do not want to go that way if I can help it in any way. None of the Endos are interested in using supplements to improve the condition either, and do not seem to be aware of any of the newer studies done on supplementing and hyperthyroidism, or remission and the role of antibodies.

Thank you,



That's fine, I assumed you would be paying for the blood test out of your own pocket, bit of a silly assumption really, sorry. PTU works by inhibiting (one type) of the conversion of T4 to T3, so the fT4 figure isn't so important. With hyperthyroidism, or Graves', the thyroid can produce more T3 than usual. I assume they switched you to PTU because it might be safer if you are breast feeding, I don't know anything about this, just guessing.

1 like

Good guess on the PTU - only something like 0.01% of the dose passes into the breastmilk as opposed to Carbimazole which passes at a rate 100 times higher (something like this), even though PTU is being recognised as a lot more toxic than originally thought, and I believe it does not affect antibodies levels.

Thank you for the interesting info on T3 and hyperthyroidism.


İf you dont mind could you tell me how you feel now ? How is your thyroid levels now ? Thanks


Hi, I've just noticed the question above - I am pleased to say I have been in remission for almost a year now. I have seen a naturopath specialising in endocrine and auto-immune conditions and she prepared a tincture based on adaptogenic herbs which together with different supplements and diet suggestions have managed to take me off the medication before the 2 year mark I had chosen with my endo to maintain the medication for. Then I stopped this tincture around June last year and I am considered euthyroid currently. I am very pleased with the result. When I stopped the herbal tincture I have also gone gluten and dairy free to keep any possible irritants to the immune system down. I have continued to take Selenium as a supplement as it is known to reduce anti TPO levels - as there is a big chance for someone treated for Graves to fall into Hashimoto's auto immune hypothyroid. So I am trying to avoid both going hyper or hypo by keeping the immune system calm. Oh, the herbal tincture also helped with my solar urticaria - sunlight allergy, another auto-immune issue I had.


Your thyroid level was high ? Any side effects or any symptoms ? Anxiety ? Low mood ? Shaking ? Sweating ? Stress?


Sorry for the late reply, I only noticed the question now - indeed there was shaking, anxiety, insomnia, feeling too hot, losing weight very fast no matter how much I was eating and being hungry all the time and then muscular pains started as I was losing muscle mass. When I went to pick up my baby one morning and realised I was so weak and shaking that I was not able to hold him I knew I was not just exhausted from having a young baby. So I went to the GP and he noticed my heart rate was 130, I was very pale, sweaty and shaking - so I ended up at the emergency room. I was in the middle of a thyroid storm.


Thank you for your reply .....


You may also like...