TG and thyroid gland disorder: Thyroid-disrupting chemicals may target the hypothalamic-pituitary-thyroid axis at multiple levels and may disrupt thyroid hormone homeostasis by interfering with the synthesis and regulation by the hypothalamic-pituitary thyroid hormones (i.e., thyrotropin-releasing hormone [TRH] and TSH), binding of thyroid hormones to distributor proteins, cellular uptake mechanisms of thyroid hormones, metabolism of thyroid hormones by iodothyronine deiodinases, transcriptional activity of thyroid hormone receptors and/or receptor activation [46, 47].