Evaluation of trace metals in thyroid tissues: Comparative analysis with benign and malignant thyroid diseases

Evaluation of trace metals at level of solid tissue can provide better information than blood or urine and, therefore, could highlight the role of metals in the etiology of organ-specific disease. The current study aimed to establish the baseline content of four essential (Mn, Cu, Zn, Se) and four toxic metals (As, Cd, Pb, U) in the healthy thyroid tissues (HTTs) by considering sex, age and smoking habits. A further aim was to examine whether differences in the content of metals exist in regard to the thyroid diseases, such as benign tumor (BT), Hashimoto's thyroiditis (HT), multinodular goiter (MNG) and thyroid cancer (TC). A total number of investigated tissue samples were 423. All metals were quantified by inductively coupled plasma-mass spectrometry (ICP-MS). It was found that the content of Cu and U was higher in HTTs of women, while the content of Zn was higher in HTTs of men. Increased content of Zn and decreased content of U was found in the group of HTTs above 50 years compared to a younger group (<50 years). Increased content of Cd, Pb and U distinguish smokers from the non-smokers. In comparison with other population groups worldwide, investigated Serbian population had up to 15 times reduced content of Se. Despite the difference in metal's profile according to biological variables, this study also demonstrated, for the first time, that each thyroid disease has its unique metal's profile. The most altered metal's content was found in tissues with HT. Contrarily, the greatest similarity in metal's content with HTTs was found in BT tissues. Based on the increased content, metal's that dominantly discriminated HTTs from the HT, MNG and TC was As, Pb and Cd, respectively. Reported results could highlight the role of toxic and essential trace metals in the not very well clarified etiology of thyroid diseases and, moreover, could provide a molecular basis for pathophysiological changes of metal's hazardous effects on thyroid health at the tissue level.