This study of 9832 athletes at three Olympic Games found that self-reported thyroid hormone use is more common than in the general population, particularly among female athletes and in power-to-weight ratio sports. However, a declining trend suggests a potential growing awareness of the lack of performance benefits and potential harms.

ABSTRACT

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.