ideal FT3 and FT4 levels on NDT

Would you agree with the following statement (from the STTM)?

From STTM: FREE T4: T4 is the thyroid storage hormone. Free in front of the T4 means you are measuring what is available and unbound. Generally, those on an optimal amount of desiccated thyroid will have a free T4 around mid-range when their free T3 is at the top and in the presence of healthy adrenals. If you have low FT4 and a mid-range or slightly higher FT3, it usually means the T4 is converting like mad to give you the T3 you do have, which means hypo.

Six months ago, I had FTs like this...and, when I added another 1 grain

27 Replies

  • Well, it's true as far as it goes. But, that's not the only definition of hypo.

    Did you post too soon? Your last sentence doesn't seem to be finished. :)

  • Oh, and I'd also want to see the TSH, in the second case.

  • Yes, sorry:-) When I added another grain, my FT4 levels ended up mid-range, but my FT3 levels out-of-range.

    Before raise (24 h after taking any thyroid meds):

    TSH <0.01 (ref 0.2--4.0)

    FT4 2.9 (ref 0.8-1.5)

    FT3 2.9 (ref 1.7-3.7)

    I actually felt pretty good back then (on Thyroid-S), but worried both my FTs were lowish, so I added another grain to the mix (mainly because it was more convenient, as it's difficult to split the Thyroid-S pills). New lab results (same ref ranges), three months later:

    TSH 0.01

    FT4 1.2

    FT3 4.6

    I honestly thought both my FTs needed be higher than they were the first time around but, since raising the dose has not made me feel better in any way, maybe I should interpret my out-of-range FT3 levels to mean I should cut back on NDT and go back to my previous dose...? My TSH has been completely suppressed for years (<0.01) as I was on synthetic combo drug Novothyral before switching to NDT...I think the last time my TSH was even remotely in (lab) range was back in 2001...!

    So, I only care about my FTs...any ideas and thoughts would be greatly appreciated. Should FT3 levels be mid-range even 24 h after taking NDT/T3, and are FT4 levels important at all? What if you cannot obtain mid-range FT4 levels and FT3 levels in the upper 1/3 of range on NDT, but need to settle for lowish FT4 levels in order to keep FT3 levels in range...? When you read about this, in theory, it sounds so FT3 and FT4 levels are always in perfect balance. I find that difficult to achieve...:-(

  • The STTM article is talking about people who aren't on any treatment, surely. Not someone taking NDT.

    I would say that someone on NDT shouldn't have an FT3 mid-range, but it's probably mid-range because 24 hours is too long a gap, and you've got a false low. And, it's very doubtful that you would obtain both Frees in the upper third of the range when taking NDT - that's for people on T4 only. When taking any kind of T3, the FT4 is going to be low.

    I find it very unhelpful to compare hypos with non-hypos and tell us that our Frees should be the same. They won't be, because we are hypo, and being hypo transcends all the rules, and turns the world up-side down. So, when you're hypo, you have to find the levels that suit you best, and to hell with the way they're 'supposed' to be.

  • Second that...after all, I find it impossible to get my FTs up where they "should" be...on T4 only, my FT3 levels were mid-range at best.

  • No, the STTM article is actually talking about people on optimal doses of NDT (from copied text):

    Generally, those on an optimal amount of desiccated thyroid will have a free T4 around mid-range when their free T3 is at the top and in the presence of healthy adrenals.

    Even though the STTM has undeniably helped many hypothyroid patients over the years, I do think it tends to be a little...categorical at times. According to the STTM, most if not all hypothyroid people need NDT, and no additional T4, and they make it sound like adrenal fatigue can be cured in no time using HC or possibly prednisone/Medrol for a short period of time. To be quite honest, I am not sure my adrenals will ever go back to working the way they did before I went hypo...I have managed to wean myself off Medrol (after five years on it), but did not feel optimal so I ended up on another product (sold OTC) containing hydrocortisone (I now take 20 mg daily and have been considering lately going back on Medrol which is what my hormone doctor prescribes for adrenal fatigue). It seems I cannot function optimally without something to support my adrenal glands, and the various products (cortex, glandulars) available on Amazon do not seem potent enough.

    So, sometimes, it feels like the STTM is talking about how things would work in an ideal world...whenever I read something on the STTM, or see it quoted somewhere, I tell myself to take it for what it is: an opinion or a recommendation, not an absolute truth.

  • Totally agree with you about STTM! It's far too dogmatic. And, a lot of it is far from the truth. They don't make allowance for the fact that we're all different. I would say that for most people - judging by the results I've seen on here - the FT4 will be a lot lower than mid-range for people on NDT. Sometimes, it's even below range. But, it doesn't matter if the person is getting the amount of T3 they need.

  • Thank you.

  • These links may be helpful:

    If you were already taking thyroid hormones adding 1 gr might be too much. I usually increased by 1/4 when I have been taking a previous dose and increase gradually. 1 gr of NDT has an 'effect' of around 100mcg of evo.

  • Thanks, Shaws, very helpful info indeed!

  • Hi

    I have been told on here that when on NDT. T4 is generally low in range and it does not matter that it is as long as T3 is at a good level.

    When my levels were tested a few months ago, my T4 was under range on 1.5 grains of NDT and T3 was 5.2, TSH was near bottom of range so according to STTM I was hypo. I felt O.K. but there was room for improvement but when I increased my dose by 1/4 grain I got palpitations.

    If I went with the STTM theory and raised my NDT to bring my T4 up to mid range then it would also raise my T3 which would bring it over range, hence the palpitations.

    Recently hypo. symptoms have crept back in so I have just had bloods re done and now my T4 has dropped even lower, T3 is about the same at 5.1 but TSH has gone up to 3.4 so I now feel hypo. but T3 is good and T3 is we are told the important one to look at so I am more confused then ever.

  • I have experienced the exact same thing recently...I tend to obsess about FT4 levels, having been told over and over again they are important (not here, but elsewhere), but I am beginning to realise that I only need low-range FT4 levels when on NDT, or my FT3 levels will end up out of range...I have tried adding as little as 1/4 grain to my current dose, but even that seems to be too, on the dose where I feel fine (no hypo or hyper symptoms, able to lose weight), my FT3 levels are midrange 24 h after latest dose (so probably much higher the previous day), my FT4 levels at bottom of range (0.9; ref 0.8-1.5), and my TSH completely suppressed. For the first time since being diagnosed with Hashimoto's disease in 2000, my antibody and anti-TPO levels are in range...I remember my anti-TPO levels being >6000 at the time of diagnosis, and now they are <8 (ref <8).

    I have started to question some things I read on the STTM...granted, it's a great site when you have just been diagnosed and have a lot of questions about thyroid disease and treatment, but I have found (through trial and error) that not everything on that site is's not a "one size fits all", no matter what they claim...

    I seem unable to maintain midrange FT4 levels and FT3 levels close to the upper normal limit, yet in range, on NDT. For some reason, my FT4 levels drop drastically whenever I am on a dose I feel fine on; as soon as I raise it, to raise my FT4 levels, my FT3 levels end up out of range. I cannot explain it, but I do feel fine so I don't worry too much about it, even if my FT4 levels are low.

    At one point, I also tried to add T4 only, but that did not make me feel better, causing me to conclude I don't need extra T4.

  • Have you read the Tired Thyroid book by Barbara Lougheed? It discusses exactly what you're asking about, namely, that some people can only get their FT4 mid-range if their FT3 is above range on NDT. There's a chart on this page (scroll down) that shows you (and I) fit Profile I: This is caused by NDT's higher T3:T4 content when compared to a human's.

    I disagree that T4 is only a storage hormone. There are T4 receptors, and it performs biological functions that T3 does not. They are obviously not essential to life, or people could not live on T3-only. I personally feel best combining NDT with T4. That's the only way I can get both values mid-range, and I swear, my brain works better with the combo than on either NDT alone or T4 alone.

  • That is VERY interesting indeed...I have in fact been considering adding T4 to the mix, but then I read about the risk of excessive rT3...but you are right, I seem unable to get mid-range FT4 levels without having supra physiological levels of FT3 at the same time. It makes sense when you consider that the T4:T3 ratio in pigs' thyroids is 80:20, and more like 90:10 or 95:5 in humans (numbers vary depending on source). But there is no doubt a pig's thyroid produces more T3 and less T4 than a human's.

    Thanks for the tip about the book, it sounds very interesting, it sounds like something that would be useful to me!

  • Hi HIFL,

    not sure if your reply is for me or anna69 or both of us, but yes I have actually purchase Barbara's book and am part way though reading it.

    My G.P. has advised to have my levels checked again this week just in case the results where "a blip".(results were lowering of T4 same T3 but TSH has raisen a lot to 3.4)

    If they do come back the same I am going to add levo. to my NDT as I cannot add more NDT as this brings my T3 too high.

    Do you happen to know, how to adjust meds.

    Before NDT I was taking 125mcg. levo. and felt O.K. but room for improvement. G.P. reduced dose to 100mcg. because of low TSH, this is when I changed over to NDT.

    Now taking 1.5 grains. Not sure whether to add levo. to 1.5 grains NDT or reduce NDT and add levo. Looking at the graph in Barbara's book there are various combinations but I am not sure which one to go for.

    Any advice would be really appreciated, thank you.

  • Hi there, You wrote "There are T4 receptors, and it performs biological functions that T3 does not." Do you by any chance know what these biological functions are or have you got reference?

  • This is the only place I've seen it discussed:

    Anecdotally, there was a discussion here that T4 may be needed by the brain to handle numbers/math. People on T3-only seem to have a problem with math, but not with verbal tasks.

  • T4 is involved in converting riboflavin into it's active form flaven adenine dinucleotide (FAD). Have taken this info from the book Stop The Thyoid Madness II, p276

  • Hello Betton,

    I know your question wasn't directed at me but I believe that T4 crosses the blood/ brain barrier. Might need to google this.

  • Both T4 and T3 cross the blood-brain barrier - they are actively transported.

    For example, see here:

    This does not imply that they are both transported equally!

  • Totally agree HIFL,

    I am on a combination of T4 and T3

    Currently I take 100mcgs levo and 20mcgs T3. I need to keep my FT4 level around mid range to feel human.

    my brain function and cognition is much improved with T4. I can literally feel a physical difference.

  • I agree with you 100%, I tried T3 only briefly and felt terrible after about a week off T4...I need T4 in addition to T3 to feel truly well. So I guess T4 has some function of its own, and is not just intended to be converted to T3...

  • After 3 months starting on Thyroid S I was on 3 grains per day. My FT3 was over the top of the range but more importantly I was getting symptoms of Hype so I reduced to two per day. Now I am on 2.5 per day and I feel OK. If you buy a pill cutter it is easy to half these pills.

  • Thanks, I have been considering it lately, but thought Thyroid-S should not be cut in half because of the coating...maybe it does not make a difference? It's true that it's easier to fine-tune the dose when you can take 1/2 or even 1/4 grain instead of a whole grain...the only thing I don't like about Thai NDT is that it only comes in 1 grain pills but, as you say, it's easy enough to buy a pill cutter...

  • I found this article very interesting and informative, and it also confirms what we discussed earlier; that is, that there is no "one size fits all" when it comes to thyroid hormone replacement:

  • As it only partly fits into this thread, I have put some of my incoherent mumblings in a separate post:

  • Very well written, indeed, thanks! Good idea also to put it in a separate post:-)

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