The thyroid system, due to its complex histological structure and functions, is
often the target of many endocrine toxins, including metals. In this regard, metals such
as Cd, Pb, Cr, Mn, Hg and Cu are known to induce thyroid toxicity in man and animals.
On the other hand, other metals are essential for the proper functioning of thyroid
system such as Se, Zn, Fe among others, and their deficiency has been related to thyroid
disruption. Metals could alter the thyroid system at many levels. In this regard, metals
could reduce iodide uptake, alter production of thyroid stimulation hormone (TSH) at
the pituitary level, alter thyroid hormones (THs) synthesis and release via many
different mechanisms at the thyroid gland level and/or could induce histopathological
alterations of the thyroid. In addition, metals could alter the metabolism of THs or
action on their receptors. This chapter is focused on the main metals reported to induce
thyroid toxicity, and the mechanisms through which their effects occur.
Keywords: Endocrine disruption, metals, thyroid, toxicity.
