Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Forensic Medicine-Toxicology

Introduction: It is well known that ionizing radiation IR exposure increases the risk of thyroid cancer; however less is known about its role in development of autoimmune thyroiditis. Objective: To assess the effects of occupational exposure to ionizing radiation on thyroid functions and the possibility of having autoimmune thyroiditis. Methods: a group of 47 cardiac catheterization workers (19 physicians, 15 nurses and 13 technicians) and another 47 job, age, and sex matched controls were subjected to investigating the serum level of T3, T4, TSH, anti-TPO, Th1 cytokines (IL2, IFNÞ), Th2 cytokines (IL10) and CD4%. Area monitoring of IR was also done using portable dose rate meter to measure local scattered radiation. Besides, annual personal exposure was monitored by TLD readings over the last 3 years Results: Area monitoring showed high level of scattered ionizing radiation inside the cardiac catheterization rooms, although dosimeter readings were within the acceptable level over the three years. Statistically significant higher level of serum TSH, anti-TPO, IL2, IFNÞ along with statistically significant lower levels of T3, IL10 and CD4% were found among the exposed compared to control groups (P<0.05). Significant positive correlation was detected between the level of anti-TPO and each of cumulative exposure index (CMI) (r=0.378 P<0.05) ,TSH ( r= 0.876 P<0.001), IL2 (r=0.847 P<0.001), and IFN Þ (r=0.685 P<0.001). Moreover, a significant negative correlation was found between anti-TPO and each of T3 (r= -0.814 P<0.001) and T4(r= -0.324 P<0.05). ANOVA and Post Hoc tests showed significantly higher level of anti-TPO and Th1 cytokines with significantly lower levels of T3, CD4% and IL10 among the physicians compared to control group Conclusion: Autoimmune thyroiditis might be one of the hazards that can be attributed to occupational exposure to ionizing radiation especially in cardiac catheterization units

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