There is a number of factors such as the thyroidectomy and limiting subtotal thyroid resection against the background of euthyroidism and initial hypothyroidism (in any extent of operation) which leads to the prediction of early postoperative hypothyroidism origin during 10 days of the postoperative period. The early postoperative hypothyroidism is accompanied by activation processes of lipid peroxide oxidation and at the same time by reduction of antioxidant protection.