SAT-398 Impact of Perchlorate Exposure on Thyroid Function and Metabolism in Endurance-Trained Female Runners

Abstract Disclosure: F. Tarkesh: None. F. Albathi: None. E. Marinik: None. B. Horton: None. E. Larson-Meyer: None. Background: Perchlorate, an environmental contaminant that can be found in drinking water and the food supply, inhibits iodine uptake and disrupts thyroid hormone production. Endurance athletes, with higher water consumption, may face elevated perchlorate exposure, potentially affecting thyroid function, thyroid antibodies and metabolic rate. Objective: This cross-sectional study investigates the associations among perchlorate exposure, thyroid function, and resting metabolic rate (RMR) in endurance-trained female runners. Methods: This study is a preliminary analysis of data collected as part of a larger study aiming to recruit 60-80 endurance-trained female runners. This subset included 23 healthy female runners aged 18-40 years (BMI: 22.1 ± 1.95 kg/m², weekly mileage: 22.2 ± 8.7 miles). Participants provided fasting blood samples for the analysis of thyroid-stimulating hormone (TSH) and thyroid antibodies, including thyroid peroxidase antibody (TPO-Ab), thyroglobulin antibody (Tg-Ab), and thyrotropin receptor antibody (TRAb). Additionally, 24-h urine samples and drinking water samples were collected and analyzed for perchlorate using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). RMR was measured by indirect calorimetry, and body composition was assessed using dual-energy X-ray absorptiometry (DXA). Spearman's rank correlation analysis was used to explore associations between perchlorate exposure and study variables. Results: Urinary perchlorate concentration averaged 3.98 ± 5.03 ng/mL. The mean (±SD) values for TSH, TPO, Tg-Ab, and TRAb were 2.14 ± 1.16 uIU/mL, 13.04 ± 5.47 IU/mL, 1.48 ± 2.66 IU/mL, and 1.01 ± 0.03 IU/L, respectively. TSH concentration exceeded the normal range (>4.5 uIU/mL) in two participants, and Tg-Ab concentration was elevated (>0.9 IU/mL) in two other participants. Urinary perchlorate concentration was positively correlated with serum TPO-Ab concentration (r = 0.5, p = 0.015). No significant correlations were observed between urinary perchlorate concentration and serum TSH, Tg-Ab, or TRAb. Conclusion: This preliminary analysis, based on a subset of participants, highlights potential association between perchlorate exposure and thyroid peroxidase antibody concentration. The study contributes valuable groundwork for exploring environmental exposures in athletic populations. These findings may be particularly relevant to female athletes, who may be at high risk for autoimmune thyroid disorders. Presentation: Saturday, July 12, 2025