Multivariate analysis of potentially toxic and essential elemental levels in human pathological thyroid tissues

The technological advancements and climate changes immensely enhanced the exposure of trace/toxic elements to mankind which may be a possible precursor of thyroid diseases including cancer development. However, the data linking them to this malignancy are generally lacking. The current study was designed to explore the role of selected elements that could contribute to the pathogenesis of thyroid diseases. Wet digestion procedure was adopted by using nitric acid perchloric acid mixture and selected elements were measured by flame and hydride generation atomic absorption spectrophotometry. The method was validated by linearity, accuracy, limits of detection and limits of quantification. Average levels (µg/g) of Zn (6.344), Ca (51.61), Cd (0.432), Se (1.995), Cu (1.781), Mg (32.54), Na (491.1), Ni (4.658), Fe (40.99) (p < 0.001) and Hg (0.047) (p < 0.01) were significantly elevated in the thyroid tissues of malignant patients, while mean contents (µg/g) of Mn (0.931), Co (3.078), Li (0.973), As (0.040), Sb (1.759) at p < 0.001, K (286.2) (p < 0.01) and Cr (1.258) (p < 0.05) showed appreciable rise in benign patients. Most of the elements exhibited significant disparities in different types of thyroid cancer patients along with higher accumulation of Cd, Cr and Li were noticed in advanced stages as compared to stage I. Multivariate principal component analysis and hierarchical cluster analysis exhibited diverse apportionment of the elements in both donor groups. The correlation study demonstrated the mutual role of essential and trace/toxic elements in the advancement of thyroid diseases. The comparison among the tissues of malignant and benign patients revealed disproportions in their elemental concentrations. The AAS technique proved to be adequate, as it exhibited good linearity, sensitivity and accuracy for the quantification of elements. Thus statistical mode of elemental analysis may be used as an additional tool for the prediction and progression of the thyroid diseases, including thyroid malignancy.