Treatment With Intramuscular Levothyroxine in Refractory Hypothyroidism

[helvella]

Given the regular appearance of patients who appear unable to tolerate levothyroxine, I thought this paper had the potential to be very interesting. And indeed the abstract is fascinating - as far as it goes. The full paper will be accessible in PubMed Central from 01/06/2020.

Eur Thyroid J, 8 (6), 319-323

Dec 2019

Treatment With Intramuscular Levothyroxine in Refractory Hypothyroidism

María de Los Ángeles Garayalde Gamboa 1 , Melina Saban 1 , Marina Ines Curriá 1

Affiliations

• PMID: 31934558

• PMCID: PMC6944946 (available on 2020-06-01)

• DOI: 10.1159/000503324

Abstract

Introduction: Orally and daily levothyroxine (LT4) is the treatment of choice for hypothyroidism. In the majority of cases, the lack of effectiveness by this way may be due to poor adherence; however, gastrointestinal malabsorption may explain more cases of thyroxine refractoriness than previously reputed, due to the number of occult forms of these disorders.

Case presentation: A 55-year-old white man with a diagnosis of low risk of recurrence of follicular variant of papillary thyroid carcinoma was treated with total thyroidectomy, 30 mCi iodine 131, and oral LT4. A year before he presented a gastric adenocarcinoma that required a partial gastrectomy. He evolved with multiple episodes of intestinal subocclusion that had to be treated with enterectomy in the first instance, then digestive rest and total parenteral nutrition. In spite of having made increases in oral LT4 dose (3 µg/kg), the patient persisted with a thyroid-stimulating hormone level >100 mIU/L. For this reason, we decided to administer intramuscular LT4.

Conclusion: Since there are no guidelines or consensus of intramuscular LT4 use, our experience and how we decided the dose and way of administration are presented in this article to contribute to future cases.

Keywords: Intramuscular levothyroxine; Levothyroxine therapy; Refractory hypothyroidism.

Copyright © 2019 by S. Karger AG, Basel.

Conflict of interest statement

The authors have no conflicts of interest to declare. Química Montpellier Laboratory provides LT4 only for parenteral use because this compound is not for sale for patients in Argentina. The laboratory delivers it to the Buenos Aires British Hospital pharmacy free of charge and given the clinical condition of the patient, without requesting any kind of compensation from the attending physicians.

pubmed.ncbi.nlm.nih.gov/319...

[Hypopotamus]

Helvella, are you asking us for our experiences in not being treated successfully with thyroxine?

[helvella Administrator in reply to Hypopotamus]

You are welcome to let us know. But no, more a case of saying that a least one patient in another country had their levothyroxine intolerance recognised and addressed in a way that I have never previously seen mentioned.

Levothyroxine injections have been reported but, from memory, always in relation to severe hypothyrodism, myxoedema coma level, and only for a very brief period.

When this full paper comes out we will, hopefully, be able to read the detail. If (as it appears to read) they are on permanent levothyroxine injections, it does raise the issue of why they can tolerate levothryoxine but notby mouth. Knowing that could be key and might even suggest other ways in which the intolerance could be overcome.

I am reminded of the recent paper about using liothyronine sulphate as a way of delivering T3 which avoiding some of the issues of straight liothyronine.

[Hypopotamus in reply to helvella]

Yes, I agree, it is interesting that thyroxine may be tolerated via an injection but not by mouth. I also wonder if taking the tablets sub lingually is significantly different to swallowing them.

Meanwhile, I still hope that there will be a supply of decent NDT.

[helvella Administrator in reply to Hypopotamus]

I strongly suspect that an awful lot of discussion about sublingual absorption has been unable to separate out what might (or might not!) be absorbed in the mouth from what gets swallowed and absorbed in the gut.

Even if some of a substance is absorbed in the mouth, quite a bit is likely to end up being swallowed. Enough, I would have thought, for any possible gut intolerance issues to be triggered. (And it is very difficult to arrange a test which stops any swallowing at all.)

Maybe measure blood levels of the substance and see how much they rise in the first few minutes (due, we assume, to absorption in the mouth) against how much gets absorbed over then next few hours?