Aim. To investigate the content of iodine (I), selenium (Se), zinc (Zn), magnesium (Mg), calcium (Ca) and vitamin D, the thyroid volume and thyroid functional state in patients with autoimmune thyroiditis (AIT) and subclinical hypothyroidism (SCH), to assess the elemental supply, possibilities and feasibility of preventive and therapeutic use of micro- and macronutrients in the early stages of the disease.

Materials and methods. 134 people were examined (13 men, 121 women). Within the entire sample, 2 groups were formed depending on the presence of functional and laboratory signs of the disease: 1st – control group consisted of 53 healthy individuals without endocrine pathology, average age – 37.9 ± 11.8 years, of which 8 were men (15.10 %), and 2nd group with AIT and SCH – 81 people, average age – 40.0 ± 11.1 years, of which 5 were men (6.17 %). Anthropometric parameters were determined: age, sex, height, weight, body mass index; thyroid functional state: total thyroid volume, concentration of thyroid-stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), level of antibodies to thyroid peroxidase (TPOAb), level of antibodies to thyroglobulin (TgAb); level of micro- and macroelement: I in urine, Se, Mg, Ca, vitamin D in serum.

Results. In the group with AIT and SCH, a significant (p < 0.001) increase in thyroid volume, TSH, TPOAb and TgAb levels and a significant decrease in thyroid hormones fT4 (p = 0.008), fT3 (p < 0.001) were found compared to the control group. In both groups, a slight iodine deficiency in the urine and a deficiency of vitamin D in the serum compared to reference values were noted. In the group of patients with AIT and SCH, a significant decrease in Se (p = 0.016), Mg (p < 0.001) and total Ca (p < 0.001) was found compared to the control. A pronounced positive correlation of Se / I (r = 0.691) was found. The statistically significant Odds ratio of AIT progression and overt hypothyroidism with reduced Mg content is OR = 2.80 (95 % CI 1.29–6.09, p = 0.0094), with reduced Ca content – OR = 7.68 (95 % CI 2.77–21.30, p = 0.0001).

Conclusions. The group with AIT and SCH and the control group have a weak iodine deficiency in the urine and vitamin D deficiency in the blood serum compared to normal reference values, which indicates a general population deficiency. In the group of patients with AIT and SCH, a significant decrease in serum Se, Mg and total Ca was found compared to the control. A significant positive correlation Se / I (r = 0.691) indicates the relationship of these trace elements and confirms their combined effect on the development of autoimmune disorders and thyroid hormonal changes. A high risk of progression of AIT and overt hypothyroidism exists with reduced Mg and Ca content.