Abstract
<title>Abstract</title> <p> <bold>Background:</bold> Several studies suggest that chronic low-dose exposure of healthcare workers to ionizing radiation impacts thyroid function. The aim of this work was to examine thyroid function and evaluate the effects of chronic radiation exposure in the occupational environment on thyroid hormone levels. <bold>Methods</bold> A comparative observational cross-sectional study was conducted on 233 participants, including 117 radiation-exposed workers and 116 non-exposed healthcare workers as a control group. Demographic data as well as some clinical features were obtained from the participants. The concentrations of thyroid hormones, comprising thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), and free thyroxine (fT4), were measured using the electrochemiluminescence immunoassay (ECLIA) method. Appropriate descriptive and analytical statistics were performed to analyze the data. <bold>Results</bold> TSH levels were significantly higher in the radiation-exposed group than in non-exposed group, whereas lower fT3 and fT4 values were found among the radiation-exposed group (p<0.05) after adjusting for possible confounding variables (age, sex, and BMI). Moreover, radiation exposure and sex interact in their effects on thyroid hormone levels. TSH levels had a positive correlation and fT4 levels had a negative correlation with working duration in the radiation exposure environment, but no significant correlation was found for T3 levels. <bold>Conclusion</bold> This study illustrates the significant effect of ionizing radiation exposure on thyroid hormone levels among radiation-exposed workers. This finding emphasizes that thyroid function should be checked repeatedly among this professional group and highlights the importance of adhering to radiation safety practices. </p>