New paper /Clinical trial : taking liquid thyroxine

Readers might be interested in the results of a clinical trial on taking liquid thyroxine - published in Thyroid: February. Here is the abstract - the results might be useful to those taking liquid thyroxine;

Background: Levothyroxine (LT4) is the recommended treatment for millions of hypothyroid patients. Current guidelines recommend that LT4 tablets be taken in a fasting state, but inability to adhere to this often leads to poor therapy compliance.

Methods: A randomized, double-blind, placebo-controlled, crossover trial was conducted in previously untreated hypothyroid patients randomly assigned to receive an oral solution of LT4 either at least 30 minutes before breakfast or directly at breakfast time. Each patient completed two six-week treatment periods, with different timing of active LT4 administration: placebo before breakfast and active LT4 at breakfast, or vice versa. At the end of each period, thyrotropin (TSH), free thyroxine (fT4), and free triiodothyronine (fT3) were measured. The primary endpoint was to verify any difference in serum TSH levels whether consuming liquid LT4 at breakfast or 30 minutes prior to breakfast.

Results: A total of 77 patients (64 females; median age 45.4 ± 3.7 years) completed the study. No statistically significant differences in serum TSH, fT4, or fT3 levels were observed whether LT4 was taken at breakfast or 30 minutes before, in a fasting state. No significant effect from the sequence of regimens, breakfast composition, and/or concomitantly administered drugs was observed on the dose of LT4 administered, or on the post-treatment serum TSH values.

Conclusions: The TICO study suggests that a liquid LT4 formulation can be ingested directly at breakfast, thus potentially improving therapeutic compliance. This observation is of considerable clinical relevance, since non-adherence to LT4 therapy requirements is more likely to cause variability in serum TSH concentrations.

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  • The question is, how likely would it be to get liquid prescribed? I have a suspicion it would be like trying to get blood out of a stone ;)

  • The real trouble with tablets is the problem of consistent bioavailability, source to source. By definition, liquid T4 must be consistent, and the study shows it isn't compromised by accompanying food, unlike tablets whose dissolving in the stomach may be affected by food. I suppose the real reason for tablets is otherwise a cost of containing vessels, ease of transportation, ease of storage and better stability at room temperature but my wife has often noted changes in her response to tablets according to where they came from.

  • Conclusions: The TICO study suggests that a liquid LT4 formulation can be ingested directly at breakfast, thus potentially improving therapeutic compliance. This observation is of considerable clinical relevance, since non-adherence to LT4 therapy requirements is more likely to cause variability in serum TSH concentrations.

    I suspect that some patients who are assumed to be non-compliant because of fluctuating TFTs may be people who might change the time of their testing quite randomly i.e. testing early on some days and mid - late afternoon on others. Or they may have taken their levo an hour before testing, or not at all for nearly 24 hours. Or they may take their levo on an empty stomach or immediately after a meal, and would carry out the same random behaviour when they are tested.

    Since most doctors aren't aware of the importance of consistent testing for TFTs, and in some cases deny that time of day makes a difference, I don't think research like the above is going to make much difference to behaviour "at the coal face", even though I agree it is interesting. If doctors don't know the importance of keeping conditions similar for testing purposes, it goes without saying that their patients won't either, in most cases.

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