IMR Press / FBL / Volume 25 / Issue 2 / DOI: 10.2741/4803

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.

Open Access Review
Iodothyronine deiodinases and reduced sensitivity to thyroid hormones
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1 Endocrinology Unit, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma – Università Cattolica del Sacro Cuore
2 Institute of Biochemistry and Clinical Biochemistry, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma
Front. Biosci. (Landmark Ed) 2020, 25(2), 201–228; https://doi.org/10.2741/4803
Published: 1 January 2020
(This article belongs to the Special Issue Digging deep into thyroid pathophysiology)
Abstract

Iodothyronine deiodinases are selenoproteins that regulate thyroid hormone metabolism. Of the three types of deiodinases, type 2 is the major regulator of intracellular triiodothyronine concentration in both the hypothalamus and pituitary, and therefore the major regulator of thyrotropin secretion. A defect in iodothyronine deiodinase activity can lead to a reduced sensitivity to thyroid hormones action and the most recent literature includes these defects in the so-called “syndromes of reduced sensitivity to thyroid hormones”. To date, the pathogenic variants of the selenocysteine insertion sequence-binding protein 2 (SECISBP2) gene are the first and only inherited disorder of iodothyronine metabolism described. Moreover, there is a growing interest in understanding the possible role of polymorphisms of DIO1 and DIO2 genes in some pathological conditions and in determining the requirement of levothyroxine replacement and the role of combined levothyroxine-liothyronine therapy in carrying subjects affected by hypothyroidism and who need replacement therapy. Results on this topic are still conflicting and more studies are needed to assess the efficacy of combined levothyroxine-liothyronine replacement therapy in this subset of patients.

Keywords
Iodothyronine Deiodinases
Thyroid Hormone
Hypothalamus–Pituitary–Thyroid Axis
SECISBP2
DIO Polymorphism
Reduced Sensitivity To Thyroid Hormone
Review
Figures
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