According to a randomized trial, administering a 15% higher dose of levothyroxine with breakfast maintained stable thyroid-stimulating hormone (TSH) levels. It was associated with improved patient well-being compared to traditional fasting administration in individuals with hypothyroidism. The new study has been published in the Journal of Clinical Endocrinology & Metabolism. The study was conducted by Jeresa W. and colleagues.
This randomized controlled trial recruited adult patients with adequately controlled hypothyroidism. Patients were randomly assigned either to continue with their current fasting LT4 medication or change to a non-fasting medication with breakfast while increasing their LT4 dose by 15%. They were monitored every six weeks for thyroid function tests, such as TSH, free thyroxine levels (FT4), and total triiodothyronine levels (TT3). Doses could be modified as needed.
The main efficacy variable was TSH value stability, where stability was considered if two sequential TSH levels were in the normal range and no more than 1 mIU/L from baseline. Patients were followed for up to 24 weeks or until stabilization. After completing the initial phase, those in the fasting group received the option to switch to non-fasting intake with similar observation.
A total of 88 patients were randomized, with 80.7% females. The median age was 62 years (interquartile range, 49-69 years). Forty-three patients were assigned to the fasting group, and 45 to the breakfast intake group. All the participants had stable hypothyroidism at baseline and started treatment with LT4.
Key Findings
The stability of TSH was reached at equal proportions among both groups.
Among the fasting subgroup, 74.4% (95% confidence interval, 61.0%-88.0%) attained stable TSH levels, while 73.3% (95% confidence interval, 60.0%-87.0%) achieved the same results among breakfasters, with data showing no statistical significance between the methods.
Similar outcomes were seen among patients who changed from fasting to not fasting to consume their regimens.
Besides the biochemical response, patient-reported outcomes also favored the breakfast group.
The proportion of patients experiencing improvement of self-perceived well-being was higher at 33.3% in the breakfast group than in the fasting group at 16.3%.
The preference for non-fasting medication was greater at 76.2% in the breakfast group compared to the fasting group at 44.2% (p<0.001).
A greater number of participants chose to continue taking LT4 medication during breakfast at the end of the study, at 88.9%.
In a group of adult patients with well-managed hypothyroidism, a 15% increased dose of levothyroxine co-administered at breakfast in comparison with fasting resulted in a TSH level that was equally stable. Such a patient-focused therapeutic option is an alternative choice for fasting and can potentially optimize patient compliance.
Reference:
Jeresa I A Willems, Daan J L van Twist, Floris Helmich, Thijs Sluiter, Marco Medici, Robin P Peeters, Roderick F A Tummers-de Lind van Wijngaarden, Fasting vs. Non-Fasting, Dose-Adjusted Levothyroxine Ingestion In Hypothyroidism: A Randomized Clinical Trial, The Journal of Clinical Endocrinology & Metabolism, 2025;, dgaf686, https://doi.org/10.1210/clinem/dgaf686
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