Regarding the effects of kidney function on thyroid function, there is an increased prevalence of hypothyroidism and subclinical hypothyroidism in chronic kidney disease (CKD) patients (2, 3), for which several mechanisms were reported, including a decrease in thyrotropin-releasing hormone (TRH) due to uremia (4, 5), thyroid status alterations (i.e., elevation of thyroid-stimulating hormone (TSH) and low thyroxine (T4) and/or triiodothyronine (T3)) by metabolic acidosis (6, 7), and retention of iodine due to a reduction in iodine clearance (8). This evidence concerns the gene TRH and hypothyroidism.