Differences of Relationships between Iodine and Some Chemical Elements in Normal Thyroid and Thyroid Benign Nodules Revealed by Neutron Activation and Inductively Coupled Plasma Atomic Emission Spectrometry

Thyroid benign nodules (TBN) are the most common lesions of this endocrine gland. The etiology of TBN is not clear. The aim of this exploratory study was to examine differences in the content of such chemical elements (ChEs) as Al, B, Ba, Br, Ca, Cl, Cu, Fe, I, K, Li, Mg, Mn, Na, P, S, Si, Sr, V and Zn, as well as differences in I/ChEs content ratios in tissues of normal thyroid and TBN. Thyroid tissue levels of ChEs were prospectively evaluated in 105 apparently healthy persons and in 79 patients with TBN. Measurements were performed using neutron activation analysis combined with inductively coupled plasma atomic emission spectrometry. It was observed that in TBN the mass fraction of Al, B, Br, Cl, Cu, Fe, Li, Mn, Na, P, S, Si, V, and Zn were higher whereas mass fractions of Ca and I were lower than in normal tissues of the thyroid. It was found also that the I/Al, I/B, I/Br, I/Cl, I/Cu, I/K, I/Mg, I/Mn, I/Na, I/P, I/S, and I/Zn mass fraction ratios in TBN were significantly lower the normal levels. Furthermore, it was shown that the levels of Al, B, Ba, Br, Ca, Cl, Cu, Fe, I, K, Li, Mg, Mn, Na, P, S, Si, Sr, V and Zn contents in the normal and affected thyroid gland were interconnected and depend on the content of I in thyroid tissue. Because I plays a decisive role in the function of the thyroid gland, the data obtained allow us to conclude that, along with I, such ChEs as Al, B, Ba, Br, Ca, Cl, Cu, Fe, I, K, Li, Mg, Mn, Na, P, S, Si, Sr, V and Zn, if not directly, then indirectly, are involved in the process of thyroid hormone synthesis. It follows that for the normal functioning of the thyroid gland, it is necessary to maintain an adequate concentration of I in its tissue, balanced with the levels of other ChE. An imbalance between I content and levels of other ChEs in the thyroid gland may be one of the causes of nodular neoplasms.