Abstract
<title>Abstract</title> <p>Purpose To assess the association between adherence to a Mediterranean dietary pattern and thyroid-related quality of life in levothyroxine-treated women with Hashimoto thyroiditis, while accounting for physical activity, sitting time, body mass index (BMI), thyroid-stimulating hormone (TSH), levothyroxine dose, and comorbidity burden. Methods This multicenter cross-sectional study included 143 women aged 18–65 years with documented Hashimoto thyroiditis and primary hypothyroidism who had received a stable levothyroxine dose for at least 12 weeks. The primary outcome was the ThyPRO-39 composite score. Mediterranean diet adherence was assessed with the 14-item Mediterranean Diet Adherence Screener, physical activity with the IPAQ-SF, and anthropometric and central laboratory measurements included BMI, TSH, free thyroxine, and anti-thyroid peroxidase antibodies. Multivariable linear regression with center fixed effects and HC3 robust standard errors was used. Results Mean age was 41.2 ± 10.5 years, mean BMI 27.0 ± 3.5 kg/m², and mean ThyPRO-39 composite score 46.8 ± 11.1. Greater Mediterranean diet adherence was associated with a lower, more favorable ThyPRO-39 score (β = −2.53 per 2-point increase; 95% CI − 4.18 to − 0.88; p = 0.003). Greater physical activity and less sitting were also associated with better scores, whereas higher BMI, higher TSH, and more comorbidities were associated with worse scores. Levothyroxine dose was not independently associated with ThyPRO-39. Conclusion Greater Mediterranean diet adherence was associated with better thyroid-related quality of life. The cross-sectional design precludes causal inference, and prospective confirmation is required.</p>