New article regarding once-daily T3 administration

A new article has appeared in the journal Thyroid which may be of interest here. First it shows that T3 administration does not return TSH values to the levels seen by using T4. Secondly it shows the  "spikes" in T3 that occur over  the euthyroid range shortly after taking the dose. The reference is:


J Jonklaas & D Burman 

Daily Administration of Short Acting Liothyronine is Associated with Significant Triiodothyronine Excursions and Fails to Alter Thyroid-responsive Parameters (doi: 10.1089/thy.2015.0629)

Again this suggests multiple T3 dosing is safer during the day.

28 Replies

  • Thank you diogenes and here is the paper:

  • So despite peaks and troughs:  'Preference for liothyronine therapy increased from 6% to 39% over the study period.'


  • Only been able to look at the abstract for the moment.  As far as I remember most trials of combination therapy used twice daily administration not once daily as this paper claims.  Perhaps the TSH did not return to the same levels as L-T4 therapy because the L-T3 dose was too low?  (will need to see the details).  This study does dismiss the claims of some patients that 'T3 always suppresses TSH' - it depends on the dose.

    One wonders what the purpose of this paper was.  Why look for hyperthyroid symptoms and not hypothyroid?  It is so frustrating that low quality research like this is financed and published when so much quality research is rejected.

  • Completely agree. The most anyone was on was 45mcg of liothyronine by the end of the trial if I've read that right - not a replacement dose for many, I'd have thought?  Yet there was still a striking increase in satisfaction with liothyronine - despite it being kept at a low dose. Tells you everything you need to know, really, doesn't it?

  • he TSH levels were high. To me that indicates under dosage.  

    But i query the administration of twice daily T3 a.m. and noon when natural circulating levels rise about 10 p.m. and start to fall about 10 a.m. Why not apply the hormone to harmonize with the normal physiologica pattern of a healthy human instead of imposing an increase in that level at a time of day when it would naturally be decreasing?  

    Improving metabolism during sleep when the body is getting a chance to heal from the daily activities would make sense to me and it seems makes sense to mother nature. But there's all this alternate dosing going on.  

  • Most people take T3 containing medication morning and late evening, the same for the trials.  I haven't heard of anyone taking it am and noon, that would be daft.  Have I missed something, I can't see a reference to noon.

  • Around here they do and my endocrinologist when I told her I was taking the second dose at 9:30 p.m. "your body doesn't need the energy when you are sleeping".

  • OMG, my Endo said just that!  Take in a.m. with Synthroid and again at noon!

  • Taking L-T3 morning and evening evens out the dose and is closer to the normal cycle.  I have found that it is the night time dose that really matters.  If I get it right I go to sleep reasonably easy and am mentally restored the next day.  If the dose is too high it is difficult to get to sleep, if the dose is too low my sleep is non-restorative.  You need lots of hormone at night, the brain is very active during sleep.

  • Jimh111, gabkad and guysgrams the European Thyroid Association recommends with regard to combination treatment  "Whereas L-T4 can be given once daily, the daily L-T3 dose should be divided (if possible) in two doses (one before breakfast and the largest one before sleeping) (2/+00)."

  • Yea, I've seen this.  They don't say why the largest (sic) one should be before bedtime.  It could be because fT3 levels will have dropped further due to the long period between breakfast and bedtime.  I split 50/50 with an extra 5 mcg at bedtime if the dose isn't a multiple of 10 mcg.  Also taking the larger dose at bedtime means that if the dose is too high you will have difficulty getting to sleep and so this is a safety net.

  • Jimh111,

    I assume it is because T3 level is highest between 01-03.00.

    My endo recommended largest dose with L-T4 morning, smallest bedtime.  I've tried both methods, and taking one daily dose morning or bedtime.  None affects my sleep.  I'm slow to wake so I follow my endo's instruction in the hope it will kick start my day but it hasn't so far :-D

  • I'd take the larger dose at night.  I find on the right dose I need seven or eight hours sleep.

  • Clutter, the doctors need educating.  I don't know where they get their ideas about dose timing.  

  • Gabkad,

    A couple of years back there were lots of articles about the superior benefits of dosing several medications according to circadian rhythms.  Gone quiet since but hopefully it's still being researched.

  • A normal replacement dose of L-T3 is quoted as 40 - 60 mcg in 2 - 3 divided doses by the manufacturers.  However, this may presume that in some cases it is used for TSH suppression after thyroid cancer.  I think about 40 mcg would be a normal replacement dose for hypothyroidism.

  • Not disagreeing with jimh111, but...

    I suspect that in the UK the typical dose would be 40 or, possibly, 60. But in the USA it would be 50 or, possibly, 75.

    That is, almost nothing to do with the patient and everything to do with the dosage of the available tablets.

    Interestingly, some makes are available in 50 and/or 100 microgram dosages! E.g. Henning Thybon.

  • Gsmith13,

    There isn't a 'norm' it will depend on how much the patient needs to bring down TSH and raise FT3 to required levels.

    I was prescribed 60mcg daily after thyroidectomy to suppress TSH <0.1.  I see many members who still have their thyroid taking higher doses without being over replaced.

  • TSH is a useless way to measure as its not a thyroid hormone. 

  • TSH is useful to measure the comparative potency of levothyroxine and liothyronine (at least in the pituitary) until there are better biochemical markers of thyroid hormone activity.  As regards measuring hypothyroidism in the patient, whilst an elevated TSH can indicate primary hypothyroidism it is not much use for diagnosing other forms of hypothyroidism or monitoring treatment.  There is no evidence to show a link between TSH and hypothyroid signs and symptoms.

  • Gsmith13,

    Endocrinologists don't generally rely on TSH only.  Mine order TSH, FT4 and FT3.  Hospital lab declined to analyse FT3 once when TSH wasn't suppressed.  I'm not aware there is anyway to measure what thyroid hormone levels are at a cellular level.

  • Interesting you say that Clutter.  At my last appointment with mine she said see you in 6 months and gave me a lab order for TSH only.  I am on Synthroid .137mcg and Lithothyroine .5mcg twice daily.  Last results my TSH was .011 and Ft3 3.9 (2.0-4.4) Free T4 1.67 (.82-1.77).  She also told me to chnage how I took my Synthroid.  6 days normal and 7th day cut the pill in half because my TSH was too low!  I can tell I'm going to have problems with her going forward I think.  All she is interested in is my TSH apparently even though I am taking T3 meds too.


  • Guysgrams,

    If you're paying a consultation fee and lab fees why not insist on TSH, FT4 and FT3.  My heart sinks when TSH testing only is done.  My TSH was suppressed but my FT3 at 3.1 was below range.  Not that my endo cared at the time.  Funnily enough, 2 years later, he said he didn't want my dose reduced further because he didn't want FT4 14 or FT3 5.0 to drop.

  • Since I didn't get this order until I was walking out the door and from an assistant I was hard pressed to get it changed.  I am going to order my own tests here as I didn't do as she suggested with the cutting the pill in half on the 7th day either.  I feel much much better and don't really want to jink things if there is nothing wrong with the way things are right now.  It has now taken an entire year to just get to some sort of normal with a bit of energy so not going backwards for anyone!

  • Guysgrams,

    If you choose to ignore the advice to reduce at least you won't run short of tablets :-D

    The co-endo I hadn't seen for 2 years felt my TSH 0.01 could be less suppressed and reduced dose by 12.5mcg.  6 weeks later TSH was <0.01.

  • Gsmith,

    How is thyroid resistance diagnosed?

  • Thyroid hormone resistance is usually diagnosed through having normal TSH, but FT4 and FT3 elevated well above their reference ranges. The resistance is throughout the body, involving all organs. In a way it mimics but to a much greater extent, the "poor converter" syndrome that many here suffer from. The phenomenon is thus likely to have a spectrum ranging from mild-to-moderate inferior conversion all the way to absolute resistance. However, only the absolute situation has been given the name. About 1/40000 people suffer from high resistance. The receptors for the hormones are deficient.

  • Thanks, Diogenes.

     I shudder to think how many people are misdiagnosed as hyperthyroid and treated with anti-thyroid drugs.

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