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Drug-induced thyroid dysfunction
Published in David S. Cooper, Jennifer A. Sipos, Medical Management of Thyroid Disease, 2018
Victor Bernet, Robert C. Smallridge
Medications known to reduce T4 to T3 conversion include amiodarone, glucocorticoids, gallbladder dyes, such as ipodate and iopanoic acid and propranolol and nadolol in high doses, and propylthiouracil. Amiodarone inhibits T4 5¢-monodeiodination which can lead to a rise in serum T4 and rT3, a concomitant decline in serum T3, and a secondary rise in serum TSH levels (96). These changes typically resolve within 3-6 months of initiation of therapy or with discontinuation of amiodarone. If the serum TSH remains elevated after more than 3–6 months, the patient can be considered to have amiodarone-induced hypothyroidism. If amiodarone needs to be continued, treatment with levothyroxine should be initiated, but levothyroxine doses needed to normalize serum TSH levels may be higher than expected due to inhibition of T4 to T3 conversion as previously discussed (97). The radiocontrast agents ipodate and iopanoic acid also inhibit T4 to T3 conversion, but are no longer available in the United States (98).
Towards a science-based testing strategy to identify maternal thyroid hormone imbalance and neurodevelopmental effects in the progeny—part III: how is substance-mediated thyroid hormone imbalance in pregnant/lactating rats or their progeny related to neurodevelopmental effects?
Published in Critical Reviews in Toxicology, 2022
M. Sue Marty, Ursula G. Sauer, Alex Charlton, Rashin Ghaffari, Davy Guignard, Nina Hallmark, Bethany R. Hannas, Sylvia Jacobi, Heike-Antje Marxfeld, Stephanie Melching-Kollmuss, Larry P. Sheets, Daniel Urbisch, Philip A. Botham, Bennard van Ravenzwaay
Since the summer of 2020, the ECETOC T4 TF continuously performed search queries in PubMed (https://pubmed.ncbi.nlm.nih.gov/ [accessed 2022 August]) to identify potentially relevant publications addressing thyroid- and brain-related effects upon in utero/lactational exposure to thyroid-active substances (see Supplementary Information SI-2 for details on the literature searches and on the selection of relevant publications and case study substances). The final selection of the fourteen case study substances was closely linked to the identification of relevant publications. For example, carbamazepine, perfluorooctane sulphonates (PFOS) and iopanoic acid ended up not being selected as case study substances due to the unavailability of relevant publications (see Supplementary InformationTable SI-1, Spreadsheet “Examples Excluded Studies Substances”).