Levothyroxine Treatment and the Risk of Cardiac Arrhythmias – Focus on the Patient Submitted to Thyroid Surgery

Zoran Gluvic, Milan Obradovic, Alan J. Stewart, Magbubah Essack, Samantha J. Pitt, Vladimir Samardzic, Sanja Soskic, Takashi Gojobori, Esma R. Isenovic

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Levothyroxine (LT4) is used to treat frequently encountered endocrinopathies such as thyroid diseases. It is regularly used in clinical (overt) hypothyroidism cases and subclinical (latent) hypothyroidism cases in the last decade. Suppressive LT4 therapy is also part of the medical regimen used to manage thyroid malignancies after a thyroidectomy. LT4 treatment possesses dual effects: substituting new-onset thyroid hormone deficiency and suppressing the local and distant malignancy spreading in cancer. It is the practice to administer LT4 in less-than-high suppressive doses for growth control of thyroid nodules and goiter, even in patients with preserved thyroid function. Despite its approved safety for clinical use, LT4 can sometimes induce side-effects, more often recorded with patients under treatment with LT4 suppressive doses than in unintentionally LT4-overdosed patients. Cardiac arrhythmias and the deterioration of osteoporosis are the most frequently documented side-effects of LT4 therapy. It also lowers the threshold for the onset or aggravation of cardiac arrhythmias for patients with pre-existing heart diseases. To improve the quality of life in LT4-substituted patients, clinicians often prescribe higher doses of LT4 to reach low normal TSH levels to achieve cellular euthyroidism. In such circumstances, the risk of cardiac arrhythmias, particularly atrial fibrillation, increases, and the combined use of LT4 and triiodothyronine further complicates such risk. This review summarizes the relevant available data related to LT4 suppressive treatment and the associated risk of cardiac arrhythmia.
Original languageEnglish (US)
JournalFrontiers in Endocrinology
Volume12
DOIs
StatePublished - Nov 4 2021

Bibliographical note

KAUST Repository Item: Exported on 2021-11-11
Acknowledged KAUST grant number(s): BAS/1/1059-01-01, FCC/1/1976-17-01, OSR#4129
Acknowledgements: This work was funded by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Contract No#451-03-9/2021-14/200017) and KAUST grant OSR#4129 (awarded to EI and VBB), which also supported MO. ME has been supported by the KAUST Office of Sponsored Research (OSR) Award no. FCC/1/1976-17-01, and TG by the King Abdullah University of Science and Technology (KAUST) Base Research Fund (BAS/1/1059-01-01).

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism

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