[Correlation analysis of low-dose X-ray ionizing radiation and thyroid function in radiation workers]

Objective: To investigate the effect of low-dose X-ray ionizing radiation on thyroid function of radiation workers. Methods: From January to December 2021, a total of 1039 medical workers in some tertiary hospitals in Wuhan were selected as the survey subjects, of which 518 radiation workers were selected as the exposure group, and 521 non-radiation workers were selected as the control group. The general conditions of the two groups were collected, and 5 indicators of thyroid function were measured, including total thyroxine (TT(4)) , total triiodothyronine (TT(3)) , free triiodothyronine (FT(3)) , thyroid stimulating hormone (TSH) , and free thyroxine (FT(4)) . The annual cumulative dose of ionizing radiation exposure in the exposure group was collected. Pearson χ(2) test and independent sample t test were used to compare the general conditions, 5 indicators of thyroid function and abnormal rate between the two groups. Linear regression model was used to analyze the correlation between the annual cumulative dose and 5 indicators of thyroid function in the exposure group. Binary logistic regression was used to analyze the influencing factors of thyroid dysfunction in the exposure group. Results: The TT(4) levels of the workers in the control group and the exposure group were (7.95±1.07) μg/dl and (8.26±1.41) μg/dl, respectively, and the FT(4) levels were (16.33±2.19) pmol/L and (17.15±2.42) pmol/L, respectively, the rate of thyroid dysfunction was 4.80% (25/521) and 8.49% (44/518) , and the above differences were statistically significant (P<0.05) . Linear regression analysis showed that the annual cumulative dose of the exposure group was significantly correlated with TT(4), TT(3), FT(4), and TSH (P<0.05) . For every 1 mSv increase in the annual cumulative dose, TT(4) increased by 1.661 μg/dl, FT(4) increased by 1.422 pmol/L, TT(3) decreased by 0.113 ng/ml, and TSH decreased by 0.731 μIU/ml. Binary logistic regression analysis showed that the older the radiation workers, the higher the risk of thyroid dysfunction (OR=1.080, 95% CI: 1.016-1.148, P=0.013) ; the greater the annual cumulative dose, the higher the risk of thyroid dysfunction (OR=6.400, 95%CI: 1.796-22.811, P=0.004) . Conclusion: The annual cumulative dose of low-dose X-ray ionizing radiation is positively correlated with thyroid function TT(4) and FT(4) of radiation workers, and negatively correlated with TT(3) and TSH; the greater the age and annual cumulative dose, the higher the risk of thyroid dysfunction.