Self-Reported Use of Thyroid Hormones by Athletes at the Olympic Games

Thyroid hormones (TH) are widely used for treatment of hypothyroidism or thyroid cancer in medical practice, but their use among elite athletes without thyroid disease remains controversial. Despite lacking clear ergogenic benefits, some athletes reportedly use thyroxine (T4) and/or triiodothyronine (T3) with the belief that they enhance performance or facilitate weight management. This study investigates self-reported TH use by athletes at the Tokyo 2020, Beijing 2022, and Paris 2024 Olympic Games, analyzing trends based on sex, age, country, and sport. Across these three events, 1.7% of tested athletes reported TH use, with reported use higher among females and in explosive power sports, which is higher than expected for the youthful Olympic participants studied. However, TH use has declined to 1.3% at Paris 2024 compared to the previous Games (Tokyo 2020: 1.8%; Beijing 2022: 2.7%). Whether this decline is due to a growing awareness of the potential harms and/or lack of performance benefits could not be determined by this study.