61 GAŁĄZKA, Jakub. The potential usage of thyroid hormones as sport doping - a mini-review. Quality in Sport. 2022;8(3):61-65. eISSN 2450-3118. DOI http://dx.doi.org/10.12775/QS.2022.08.03.007 https://apcz.umk.pl/QS/article/view/41361 The journal has had 20 points in Ministry of Education and Science of Poland parametric evaluation. Annex to the announcement of the Minister of Education and Science of December 21, 2021. No. 32582. Has a Journal's Unique Identifier: 201398. Scientific disciplines assigned: Economics and finance (Field of social sciences); Management and Quality Sciences (Field of social sciences). Punkty Ministerialne z 2019 - aktualny rok 20 punktów. Załącznik do komunikatu Ministra Edukacji i Nauki z dnia 21 grudnia 2021 r. Lp. 32582. Posiada Unikatowy Identyfikator Czasopisma: 201398. Przypisane dyscypliny naukowe: Ekonomia i finanse (Dziedzina nauk społecznych); Nauki o zarządzaniu i jakości (Dziedzina nauk społecznych). © The Authors 2022; This article is published with open access at Licensee Open Journal Systems of Nicolaus Copernicus University in Torun, Poland Open Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author (s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non commercial license Share alike. (http://creativecommons.org/licenses/by-nc-sa/4.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited. The authors declare that there is no conflict of interests regarding the publication of this paper. Received: 12.11.2022. Revised: 19.11.2022. Accepted: 19.12.2022. The potential usage of thyroid hormones as sport doping – a mini-review Jakub Krzysztof Gałązka1 1 - Students’ Scientific Association at the Department and Clinic of Endocrinology, Diabetology and Metabolic Diseases, Medical University of Lublin, Jaczewskiego 8, 20-954 Lublin, Poland; ORCID 0000-0003-3128-773X; e-mail: jakubgalazka2@wp.pl Abstract A thyroid gland is one of the most important organs of a human body. Thyroid hormones, at least in physiological concentration, have anabolic features. The aid of this review is to summarize knowledge on potential usage of thyroid hormones in sport doping. Thyroid hormones play a crucial role in skeletal muscles physiology. The exposition to T3 and T4 may improve myogenesis, muscles regeneration and muscles blood blow. In a long-time perspective, those hormones may help in reducing body weight. According to those mechanisms, thyroid hormones may be considered as a plausible agent in sport doping. However WADA guidelines does not include T3 or T4 in a list o sport http://dx.doi.org/10.12775/QS.2022.08.03.007 https://apcz.umk.pl/QS/article/view/41361 mailto:jakubgalazka2@wp.pl 62 doping substances, the debate on their inclusion is on-going, and the physicians should be aware of thyroid hormones effects on human metabolism from sports medicine perspective. Keywords: thyroid hormones, triiodothyronine, thyroxine, skeletal muscles, sport doping Introduction A thyroid gland is one of the most important organs of a human body. Thyroid hormones, at least in physiological concentration, have anabolic features. Due to this, the more common symptoms of hyperthyroidism are sweeting, elevated body heat and psychosomatic hyperactivity (f.x. hyperthyroidism is more prevalent among the patients with first episode of mania) (Goyal et al., 2021) . But on the other hand, symptoms similar to mentioned, appeals to be useful from the perspective of a sport doping. The aid of this review is to summarize knowledge on potential usage of thyroid hormones in sport doping. Methods To access necessary articles, the literature review was performed using two databases – PubMed and GoogleScholar. Used keywords included “thyroid hormones” and “sport” or “sport doping”. Articles written in languages other than Polish and English were rejected. Results In skeletal muscles, the enlarged expression of type 2 iodothyronine deiodinase (DIO2) was detected, what links with the crucial role of thyroid hormones in muscles development and regeneration after injury (Salvatore et al., 2013) . Triiodothyronine (T3) stimulates the expression of myosin heavy chain, increases mitochondrial reactions and the relaxation– contraction rate (Bloise et al., 2018) . Even during pregnancy, the embryonal exposition to maternal thyroid hormones results up with enhanced myogenesis(Gao et al., 2022). The role of thyroid hormones in muscles regeneration may be the cause of correlation between T3 and 63 thyroxine (T4) concentration and skeletal muscles quantity among the old (di Iorio et al., 2021) . Thus, the significant impact of thyroid hormones on myogenesis and muscle regenerations accompanies the whole human life. Thyroid hormones have protective effect on various tissues in ischemia(Lourbopoulos et al., 2021), including cardiac muscle(Zeng et al., 2021) and cortical neurons(Li et al., 2019). In according to skeletal muscles, thyroid hormones improve blood flow through vasodilatation(Selivanova & Tarasova, 2020). From the perspective of sports genomic, there is a polymorphic variant of thyroid stimulating hormone receptor (TSHR) gene named rs7144481 C, which correlates with better sport skills. This polymorphism variant results with hypersensitivity for thyroid stimulating hormone (TSH) and secondary higher concentration of T3 and T4 (Bogdan-Alexandru Hagiu & Ghiciuc, 2020). Thyroid hormones have also effect on lipids metabolism. Their enhancement of thermogenesis may result up with adipose tissue loss(Ribeiro, 2008). This function of thyroid hormones is concerned for usage in dyslipidemias and obesity treatment(Wiacek et al., 2021). According to current World Anti-Doping Agency (WADA) guidelines, thyroid hormones intake isn’t qualified as sport doping, in contrast to androgens and erythropoietin(Gild et al., 2022; Martínez Brito et al., 2022). Current perspective on hormonal intake in sport doping policy changes, focusing on insulin-like growth factor 1 (IGF-1), directly and indirectly – f.x. indirect effect on IGF-1 secretion may be the result of thyroid hormones(Barroso et al., 2008). On the other hand, the endocrinologists should pay attention to potential abuse of thyroid hormones to ameliorate sport skills. On the other hand, thyroid disorders are the most prevalent among young adults – the group, which sportsmen are recruited from(Gild et al., 2022). The prohibition of thyroid hormones abuse may be hard also in according to inability of differentiation from endogenous and exogenous thyroid hormones. Conclusion Thyroid hormones play a crucial role in skeletal muscles physiology. The exposition to T3 and T4 may improve myogenesis, muscles regeneration and muscles blood blow. In a long-time perspective, those hormones may help in reducing body weight. According to those mechanisms, thyroid hormones may be considered as a plausible agent in sport doping. However WADA guidelines does not include T3 or T4 in a list o sport doping substances, the debate on their inclusion is on-going, and the physicians should be aware of thyroid hormones effects on human metabolism from sports medicine perspective. 64 References Barroso, O., Mazzoni, I., & Rabin, O. (2008). Hormone abuse in sports: the antidoping perspective. Asian Journal of Andrology, 10(3), 391–402. https://doi.org/10.1111/J.1745-7262.2008.00402.X Bloise, F. F., Cordeiro, A., & Ortiga-Carvalho, T. M. (2018). Role of thyroid hormone in skeletal muscle physiology. The Journal of Endocrinology, 236(1), R57–R68. https://doi.org/10.1530/JOE-16-0611 Bogdan-Alexandru Hagiu, B., & Ghiciuc, C.-M. (2020). Sports Genomics and Sport Doping. Athens Journal of Sports, 7(3), 163–172. https://doi.org/10.30958/ajspo.7-3-2 di Iorio, A., Paganelli, R., Abate, M., Barassi, G., Ireland, A., Macchi, C., Molino-Lova, R., & Cecchi, F. (2021). Thyroid hormone signaling is associated with physical performance, muscle mass, and strength in a cohort of oldest-old: results from the Mugello study. GeroScience, 43(2), 1053–1064. https://doi.org/10.1007/S11357-020-00302-0 Gao, Y., Zhao, L., Son, J. S., Liu, X., Chen, Y., Deavila, J. M., Zhu, M. J., Murdoch, G. K., & Du, M. (2022). Maternal Exercise Before and During Pregnancy Facilitates Embryonic Myogenesis by Enhancing Thyroid Hormone Signaling. Thyroid : Official Journal of the American Thyroid Association, 32(5), 581–593. https://doi.org/10.1089/THY.2021.0639 Gild, M. L., Stuart, M., Clifton-Bligh, R. J., Kinahan, A., & Handelsman, D. J. (2022). Thyroid Hormone Abuse in Elite Sports: The Regulatory Challenge. The Journal of Clinical Endocrinology and Metabolism, 107(9), E3562–E3573. https://doi.org/10.1210/CLINEM/DGAC223 Goyal, M., Yadav, K., & Solanki, R. (2021). A study of thyroid profile in patients suffering from the first episode of mania: A cross-sectional study. Indian Journal of Psychiatry, 63(4), 395. https://doi.org/10.4103/PSYCHIATRY.INDIANJPSYCHIATRY_33_20 Li, J., Abe, K., Milanesi, A., Liu, Y. Y., & Brent, G. A. (2019). Thyroid Hormone Protects Primary Cortical Neurons Exposed to Hypoxia by Reducing DNA Methylation and Apoptosis. Endocrinology, 160(10), 2243–2256. https://doi.org/10.1210/EN.2019-00125 Lourbopoulos, A. I., Mourouzis, I. S., Trikas, A. G., Tseti, I. K., & Pantos, C. I. (2021). Effects of Thyroid Hormone on Tissue Hypoxia: Relevance to Sepsis Therapy. Journal of Clinical Medicine 2021, Vol. 10, Page 5855, 10(24), 5855. https://doi.org/10.3390/JCM10245855 Martínez Brito, D., Botrè, F., Romanelli, F., & de la Torre, X. (2022). Thyroid metabolism and supplementation: A review framed in sports environment. Drug Testing and Analysis, 14(7), 1176– 1186. https://doi.org/10.1002/DTA.3257 Ribeiro, M. O. (2008). Effects of thyroid hormone analogs on lipid metabolism and thermogenesis. Thyroid : Official Journal of the American Thyroid Association, 18(2), 197–203. https://doi.org/10.1089/THY.2007.0288 Salvatore, D., Simonides, W. S., Dentice, M., Zavacki, A. M., & Larsen, P. R. (2013). Thyroid hormones and skeletal muscle—new insights and potential implications. Nature Reviews Endocrinology 2013 10:4, 10(4), 206–214. https://doi.org/10.1038/nrendo.2013.238 Selivanova, E. K., & Tarasova, O. S. (2020). Nongenomic Effects of Thyroid Hormones: Their Role in Regulation of the Vascular System. Moscow University Biological Sciences Bulletin, 75(4), 189–198. https://doi.org/10.3103/S0096392520040094/FIGURES/2 Wiacek, M., Markuszewski, L., Tomasiuk, R., & Zubrzycki, I. Z. (2021). Relations Between Performance Enhancement Drugs and Health-defining Parameters During the Competition Preparation Period of World-class Bodybuilders. https://doi.org/10.21203/RS.3.RS-779161/V1 65 Zeng, B., Liu, L., Liao, X., & Zhang, C. (2021). Cardiomyocyte protective effects of thyroid hormone during hypoxia/reoxygenation injury through activating of IGF-1-mediated PI3K/Akt signalling. Journal of Cellular and Molecular Medicine, 25(7), 3205–3215. https://doi.org/10.1111/JCMM.16389