White spots in the questions related to selenium deficiency: about the place of selenium-containing drugs in the treatment of thyroid pathology
Authors: Buldyhina Yu.V. , Terekhova G.M. , Strafun L.S. , Shlyakhtych S.L. , Rakov O.V. 
Published: August 2020

Background. The role of selenium deficiency in the pathogenesis of thyropathies is actively discussed in the last decade, as well as the advisability and efficiency of using selenium-containing drugs in their treatment. There are extremely little data on the presence/absence of selenium deficiency in the general population of Ukraine and in patients with thyroid pathology in particular to date. Therefore, the question of expedient use of selenium-containing drugs is of great interest to both scientists and practitioners. The purpose was to study the attitude of Ukrainian endocrinologists towards the use of selenium-containing drugs in the treatment of thyroid pathology, and to investigate selenium content in the blood serum of patients with diffuse toxic goiter during antithyroid therapy in combination with prolonged use of these drugs. Materials and methods. The questionnaire was sent online to 100 endocrinologists from different regions of Ukraine, it included 6 questions: 1. Do you know about the role of selenium deficiency in the development of thyroid pathology? 2. Do you prescribe selenium drugs to patients with thyroid pathology? 3. In which thyroid pathology do you usually prescribe selenium drugs? 4. Which doses of selenium do you prefer? 5. What duration of treatment with selenium-containing drugs do you recommend? 6. Do you control the level of selenium before and after the course of therapy with selenium drugs? The study of selenium content in the blood of patients with thyropathies before and after treatment with selenium drugs was also continued in the clinic of the State Institution “V.P. Komisarenko Institute of Endocrinology and Metabolism of the National Academy of Medical Sciences of Ukraine” during 2018–2019 to evaluate their effectiveness and the time needed to eliminate selenium deficiency. The group of examined patients consisted of 35 persons: 34 women and 1 man (mean age of 48.2 ± 5.2 years) suffering from diffuse toxic goiter. According to the anamnesis, the disease duration ranged from 6 months to 5 years (2.8 ± 2.0 years on average). At the time of the examination, all the patients were in a state of euthyroidism. The determination of selenium was performed by a fluorometric method using the Hitachi MPF-4 spectrofluorimeter with the required sensitivity (approximately 0.0004 µg/ml of selenium) and an insignificant measurement error (2 %). Results. It was determined that 98 % of doctors were informed of the role of selenium deficiency in the development of thyroid pathology, but 33 % of them said that they would like to have more information. The awareness of doctors does not affect the frequency of selenium-containing drug prescriptions. Selenium-containing drugs are prescribed in thyropathies by 47 % of respondents, 35 % prescribe them sometimes, and 18 % do not prescribe at all. The doctors mainly prescribe selenium drugs in autoimmune thyroiditis with euthyroidism or subclinical hypothyroidism (77 %), in diffuse euthyroid goiter (10 %), in diffuse toxic goiter (7 %), in thyroid-associated ophthalmopathy (5 %), and in multinodular nontoxic goiter (6 %). It was found that most doctors (55 %) prescribe selenium-containing drugs at a dose of 50 to 100 µg per day, 30 % of respondents usually prescribe 100 to 200 µg per day, and only 15 % of doctors prescribe 200 µg or more. The duration of treatment course preferred by doctors is 3 months (70 %), 12 % of respondents prescribe selenium-containing drugs for 1 month, and 18 % — for 6 months. Selenium content in the blood of patients before/after the course of treatment is determined always only by 5 % of respondents, sometimes — by 6 % of respondents, and 89 % of them do not determine it at all. When studying selenium content in the blood serum of patients with diffuse toxic goiter, its level was 17.80 ± 2.59 µg/l in the study group; median — 13 µg/l (with a norm of 80–100 µg/l). All the patients were prescribed selenium-containing drugs at a daily dose of 200 μg, followed by a control study of selenium in the blood 3 and 6 months after continuous treatment. Selenium levels increased significantly to 63.88 ± 6.61 μg/l (median of 58.5 µg/l) 3 months after treatment. When controlling this indicator after 6 months, the level was 75.02 ± 9.78 µg/l (median of 78 µg/l) that was significantly higher than baseline values. Thus, a three-month course of using selenium-containing drugs (with a daily dose of 200 µg) may not be sufficient to restore the normal levels of selenium in patients with diffuse toxic goiter and selenium deficiency, requiring the continued treatment for another three months with individual control of selenium levels, or prescription of higher daily doses of the drug. Conclusions. The number of endocrinologists who know about the role of selenium deficiency in the development of thyroid pathology is 98 %, at the same time 33 % of respondents are wishing to have more information about the advisability of prescription and efficiency of selenium-containing drugs. Selenium-containing drugs are prescribed in thyroid diseases by 47 % of doctors, of these, by 77 % — only in autoimmune thyroiditis. Only 5 % of doctors prescribe selenium-containing drugs in thyroid-associated ophthalmopathy. Preference is given to the use of small doses of selenium-containing drugs (55 %) with the treatment duration no more than 3 months (70 % of respondents). The level of selenium before/after the course of selenium-containing therapy is not determined by 89 % of the respondents. In patients with selenium deficiency (17.80 ± 2.59 µg/l; median — 13 µg/l) after regular use of selenium-containing drugs (200 µg of selenium per day) for 3 months, the level of selenium in the blood increases significantly to 63.88 ± 6.61 µg/l; the median of 58.5 µg/l, but does not reach the lower limit of normal. Only 6 months after regular intake of selenium-containing drugs (daily dose of 200 µg), the level of selenium in the blood is normalized to 75.02 ± 9.78 µg/l; median of 78 µg/l, thus approaching the lower limit of normal.