Detection of liver dysfunction in patients with diffuse toxic goiter (DTG) at an early stage allows for correcting it in time with appropriate therapy; therefore, diagnosing hepatobiliary system lesions in these patients is an important medical issue. We examined 62 patients, divided into two groups depending on the duration of the disease. The first group included patients with a disease duration of up to two years, the second group – patients with a disease duration of more than two years. The study and comparison of laboratory and multiparametric ultrasound criteria of liver and thyroid dysfunction were performed. Analysis of ultrasound signs of hepatobiliary system lesions in patients in the two groups showed that they were more common in the second group. There is a correlation between the stiffness of the parenchyma of the thyroid gland and liver and the duration of the disease, the level of free thyroxine (T4f), and antibodies to thyroid-stimulating hormone receptors (ArTTG). Increased liver stiffness was more common in patients with ArTTG levels above 20 IU/ml, and the degree of F1 fibrosis was higher at T4f greater than 50 pmol/l. To assess the condition of a patient with DTG and the need to correct treatment tactics, it is advisable to use the criteria of multiparametric ultrasound examination of the hepatobiliary system and thyroid gland.