T3 blood test question

Hi everyone, just a quick question to all you knowledgeable people :) I have learned from this forum that when you are having your regular TFT blood tests that you should not take your T4 that morning until after the blood is taken. I didn't know this and have always taken it on the morning of my test but won't be doing next time. Today I have finally received T3 from my endo (fanfare!) and his secretary has booked me in for a follow up appointment on 2nd December which by the time I will need to have my blood taken will be just over two weeks. Seems a bit quick. Anyway, my question is, as T3 is fast acting do I still take my T3 the morning of the blood test or do I not take the T4 and T3 until after the blood is taken? Just for info, my endo has dropped me from 100 MCU levo to 50 mcu and 20MG T3 per day split into two doses. Morning and afternoon I guess?

Just for info, my last test had T4 in top quartile of range, my TSH @ 0.03 and my T3 @ 3.2 (3.6 - 6.5) I have had a short synacathan test and TSH antibodies test both of which were fine which is why he is allowing me to try T3

ps….I took my first 10mg of T3 this afternoon and waited for the miraculous transformation of weight loss, energy regain, and metabolism increase so that I could bin my years supply of Ex-LAx. So far nothing has happened….I guess I had better be patient :-)))

happy weekend to you all!

ops…my endo will only let me continue with T3 if my TSH increases which he is hoping the drop in Levo will facilitate however having read other posts regarding this subject I gather that the T3 might make my TSH lower…. :(

Last edited by

32 Replies

  • Querida, don't take any thyroid medication until after your blood test. You'll need to work out what suits you with T3 split dosing. I take my first dose in the morning with Levothyroxine and the second at bedtime 12/14 hours later.

    Your endo is setting T3 up to fail if he expects it raise your TSH. He should be prescribing it to raise your FT3. TSH rises in response to lack of circulating thyroid hormone. When the pituitary gland detects sufficient circulating T3, whether natural or via oral ingestion, it signals TSH to switch off.

    T3 takes 48/72 hours to get into your cells and a couple of months to metabolise so don't bin your ex-lax yet. Energy will improve as your FT3 levels increase.

  • Thank you clutter. He told me that my TSH indicates that I don't need any more t3 converting which is why my t4 is high. He said its nothing to do with conversion issues. How on earth do we deal with that attitude. He gave me t3 as he acknowledges my symptoms but will withdraw it if my TSH doesn't increase with the reduced Levo. So I guess that looks set to happen. So I have ordered a pack of tyromel from Turkey and it arrived yesterday. The pack looks a bit beaten up but I assume that it is the real deal. I have no idea what brand of t3 I have from the nhs as it is in a generic Lloyd pharmacy bottle. 13tablets. They didnnt have the full 28. The tyromel is 25mg. Do you know if it will be the same strength as the nhs stuff? So I would take half a tablet twice a day? Huge thanks for all your advice.

  • The Liothyronine from the Nhs is made by mercury pharma and used to be called Tertroxin. Then they decided to withdraw the brand name and call it a generic. There are no price controls on generics so the price for a bottle of 28 has risen fron £20 odd to around £125. This adds fuel to the argument fom the medics that t3 is of no use.

  • Thanks G. How crazy is that price when I bought 100 x 25 tiromel from Turkey for less than $40

  • Querida, UK T3 is Liothyronine and is 20mcg. Tiromel is a Turkish brand and 25mcg. Might be better to quarter the Tiromel and take three quarters, 18.75mcg.

  • OK, thank you Clutter. I will keep this in mind if he withdraws my T3 :)

  • Hi clutter, I have a quick question. I have looked at my Turkish insert with the Tiromel and think that it contains starch….has anyone ever mentioned whether this is tolerated by people with gluten sensitivity? also, in your experience, how long does it usually take if you are going to get an adverse reaction? I am guessing pretty quickly?

    Thanks so much


  • Sue, I don't read Turkish so can't translate the Tiromel PIL. Maize starch is an ingredient in UK Liothyronine and Levothyroxine. I think maize is derived from corn so shouldn't trigger a gluten reaction. UK medicines are gluten-free.

  • Please do us all a favour and absolutely insist on a Patient Information Leaflet with EVERY prescription of T3 you get.It is their responsibility to supply this information. In my view it is wholly wrong for people to get medicines without both a PIL and the batch number and expiry date. And of course that will also include the product license number, company, etc.

    Indeed, if I were not desperate at the time, I would positively refuse to accept the product other than in its original packaging. If that means going to another pharmacy, so be it.


  • Errrrm right Ok Rod. I guess you feel strongly about this! :). My husband picked them up for me or I would have questioned it. And I guess I am/was desperate as I have been waiting for more than 4 months. Thanks for your advice as always :)

  • Yes - I do! :-)

    If you had a problem, how would anyone be able to feed your bad experience back into the system to ensure a bad batch was identified and withdrawn?

    If you buy a tin of beans you can see the company responsible (supermarket, Heinz, Branston or whoever else). You like them? You can choose them again. You hate them? You can avoid them in future.

    Although you actually have no choice with regard to T3 in the UK, the principle should still apply that you can identify the people who put the product onto the market. You get that with a 19 penny pack of paracetamol - why not with a £120+ pot of pills?

    Make me the medicine tsar and I would insist on PIL, batch and expiry being supplied on every single prescription.

  • Oh please.... i wonder how he y qualified as an endocrinologist. Grrrrr. Gimme 10 minutes with him. :-((. . Your tsh will not rise if you are on t3, It will more likely drop.

    Suggest you write to Louise (admin) and ask for a copy of the pulse article, then make the endo read it., by handing it to him and standing there expectantly. Don't speak, let him read it. - he might learn how to begin to treat you.

    Great that he has given you t3, but a real shame that he has no clue why. My endo gave me t3 because he believes it is a pl,acebo.

    There is no instant miraculous transformation, so don't hold your breath.... There is just a gradual realisation that you feel brighter and things are not so tiring and tough....

    Xx. G

  • Thank you for your advice G. Seems crazy that I have to see him after only 3 weeks on the t3!

  • Hi G, I just read the pulse article (thank you) but I am not sure it will help :(. Ref below he says that the TSH must not be supressed as mine is. :((

    "While taking both hormones it is important serum TSH is normal and not suppressed. If the patient is still dissatisfied it should be made clear that the symptoms have nothing to do with thyroid disease or its treatment and perhaps issues at home and in the workplace should be addressed"

  • Just reading this thread and am interested in what you say about introducing T3, (I have just ordered my first lot, against my doctors wishes because my bloods were in normal range) the reaction I expect is exactly what you have mentioned above which is the exact reaction I am looking for, I am not looking for a quick fix I just want to feel normal. So I will be hoping to gradually feel better over the next couple of months, thanks for saying how it should feel, all I had from my endo is the bad signs to look out for which he is convinced I will get from taking the T3.

  • T3 will make TSH lower. Definitely don't take it before blood test! Takes a few days for T3 to effect change. If you have T4 conversion problem it takes time for reverse T3 to clear.

  • Thanks so much. I will def not take it before my blood test :)

  • Depends on surpressed, My tsh is 0.02 and has been so for years, apart for when the endo tried me without t3... Then it rose to 0.1 and I felt terrible. I argued that suppressed meant zero and was threatened with osteoporosis and heart failure.. Lol.

    I insisted on a dexa scan to measure my bone density about 4 years ago (when I was 54)... I had the bones of a 30 year old. So that put paid to that argument. Regular heart monitoring because my heart was going mad with any exercise eventually led to a diagnosis of exercise induced asthma. The heart goes mad trying to pump oxygen round.... After three years of messing around with asthma meds, I asked for a referral to Southampton. ( out of my area). But they have been very thorough, and have worked out my alergy triggers for asthma. ( grass and weeds) and now I have great meds which alleviate my problem... At one point they asked for thyroid testing although they said they didn't believe in t3. I refused them permission to take blood for that purpose.... There was a long thread on here.... When I next saw them they never said a word about thyroid, just it on and tried different meds.

    The point of this ramble, is that usually you have to be clued up and prepared to challenge medical opinion.

    Good luck...

    G xx

  • Thats really interesting and good to know G, thank you. I appreciate that I don't have symptoms as bad as many. My main problem is that I need to take 2/3 laxatives every day, have done for the last 6 months. Tiredness, cramp in my feet and of course I live on lettuce trying to control my weight. I am 46 and feel that I am still entitled to do what I can to feel well. I do all the other stuff, no gluten, grains etc exercise and healthy diet. When I was diagnosed my TSH was 37. As soon as I started taking levo it dropped to 0.01 and is now 0.03 with below range T3…so not straight forward but I am determined to go armed with as much information as I can. I appreciate your help :)

  • The needing laxatives is a hypo sign and something is odd if the tsh is low when free t3 is low..... Not sure what but it definitely isn't right. Anyone any suggestions? Please?

    Have you tried psyillium husk capsules from holland and barret? They work great without being too much, a couple a day does the trick..

    G x

  • Galathea, low TSH + high in range FT4 + low FT3 = conversion problem. Can be impaired DIO2 gene or just that T4 only isn't working.

  • Hi clutter, It does seem to be a bit weird my having a low TSH and a low T3 and it worries me a bit. Last September I felt a swelling in my throat and was sent for thyroid blood tests. this was the first I had heard of my thyroid! :) The results were my T4 slightly over 21.4 and my T3 at top of the range and TSH 0.02 so they said I was overactive but wanted to wait a month and test again before treating me. Prior to my throat swelling i had felt fine apart from I was surprised at being able to go to the loo without laxatives, had lost a few lbs when knowing I was eating a bit of fattening stuff now and then, and I had suffered what I thought where RSI pains in my arm and couldn't play tennis as usual but that was all. So after a month of waiting they retested me and I had a TSH of 37, a T4 at bottom of range and T3 wasn't measured. I didn't have and have never had antibodies. so they diagnosed hypo and started me on levo which made me feel better to start off with. So now I have T3 :) - day 12 and feel fine, the odd ache and pain but I have always had those but it just worries me that me TSH will get worse and does this really mean as my endo said that my body doesn't need any more T3? and really they should be reducing my meds. I have campaigned so long for T3 and now I have it I am wondering if what happened to me before RSI pain etc will happen again considering that my TSH is low. How that works is beyond me when I have significant hypo symptoms, constipation, cramps, brain fog etc. Perhaps I am rambling too much and taking up too much of your time! apologies.....its just very complex. have to see that I would be lost without all the great info on here! so thanks!

    ps....since starting T3, my brain fog is def better, I dont have the terrible hunger for sugary stuff and so far (touch wood!) I haven't had cramp in my feet at night in the last week! wahey! :)

  • Queridalady, Prior to the thyroid failing and becoming hypothyroid it isn't unusual for a burst of hyperactivity to be experienced, the failing thyroid's swan song, as it were. Feeling as if your throat was swelling would be due to the thyroid swelling to produce additional hormone.

    Low TSH, high FT4 and low FT3 on Levothyroxine means you weren't converting T4 to T3 sufficiently.

    Low TSH, low FT4 and good FT3 are to be expected on T4+T3, T3 only and NDT.

    Pituitary gland responds to circulating hormone. When T3 is low pituitary produces TSH to stimulate the thyroid gland to produce T4 for conversion to T3. Taking oral T3 means the pituitary senses sufficient circulating hormone in the blood and switches off TSH. FT4 often drops low in range or even below range because it is a prohormone or 'storage' hormone required for conversion. Taking oral T3 means you bypass the need for storage of T4 for conversion.

    You've only been taking T3 for a few days and have noticed improvement already. It will take another 2/3 months for the T3 to metabolise and work in your cells to relieve the rest of your symptoms. You may need either your T4 or T3 may need adjusting according to your blood tests but I hope your endo won't make any adjustment unless your FT3 is over range.

    Brain fog and clarity of thought were the first improvements I noticed when T3 was added to my T4. The physical symptoms took longer and hair, skin and nails were the last improvements, about 5 months after T4+T3 were optimal.

  • Hi clutter, just referring back to your reply above from some time ago. When you said after T4+T3 were optimal..... do you mean your symptoms were gone or you T4,T3 were both in top half of range please?

  • Queridalady, optimal bloods, usually in the top half/75% of range can precede the feel good factor by a few weeks.

    If symptoms are gone but bloods aren't in the optimal 50%/75% range I'd go on how you feel and not worry about the blood results. How you feel is the important thing.

  • Thank you Clutter. I am getting very confused really. I am worried about my pulse being in the 80's and after walking around, sometimes the 90's. None of it seems to make sense really. since trying the T4 T3 combo I have felt improvements but now have T4 below range and T3 just at the bottom of the range and low TSH but the pulse thing and the fact that I started feeling the muscle burn in my arm that I had before I was diagnosed…..makes me wonder if I am overmedicated? I had muscle problems in my tennis arm and what we thought was CTS for a few weeks and it was around the time (not that I knew then) that my thyroid was obviously going under and then had a swan song and went over active for a few weeks and then crashed and has been under ever since. Then my arm resolved itself So don't know whether the pulse and arm pain is because I am under or overmedicated. My BP is normal with the systolic always on the lower side towards diaststolic rather than a wider gap between them, I am not losing weight and still suffer constipation. so confused and worried…..i have stopped taking the extra T3 I was giving myself on top of the prescribed amount. don't know what I am doing really *sigh* anyway, thank you for responding to my question so quickly :) x

  • Querida, while your FT3 is under range or at the bottom of range you are not overmedicated. Oral T3 does lower TSH and FT4. You may have increased your T3 too much or too quickly. See whether your pulse normalises now you have cut the dose. Perhaps increase by a smaller amount in a couple of weeks.

  • thank you clutter…..I will monitor. i appreciate your advice.

  • Queridalady, I didn't mean to imply you have done something wrong. When I say you may have increased too much or too quickly, I mean it may have been more than you can tolerate for now. Some people are much more sensitive to T3 than others and can only tolerate very small increases.

  • No worries. I am happy to hear all your advice/thoughts clutter. perhaps I was a bit keen to up my T3 my self. I did so because after 7 weeks on my reduced T4 and T3 I had started to become unable to cope with my tennis lessons. Out if breath in minutes. Then my results showed I was below on T4 too whereas I was ok in this respect when I first took T3 and had a higher level of T4 in my system. my gp increased my T4 and I decided to up my T3 too. Perhaps too much too quickly as you say. I hope the increased T4 will help with breathlessness in tennis. I have to play. It's not an option to give up :). I am so grateful to you and the other knowledgable and helpful people on here. Thank you x

  • Queridalady, definitely only increase T4 or T3 not both at the same time. It sounds as if the endo may have reduced T4 too much when he prescribed T3. Hopefully the increased T4 will help. Give it 6 weeks and if it hasn't try another 6.25mcg T3.

  • This is the best explanation I have read on how the thyroid works and how the tests read! Thanks

You may also like...