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The Letter to Editor presents an analysis of some sections of the clinical guidelines «Diseases and conditions associated with iodine deficiency» published in No. 3 of the journal «Problems of Endocrinology» for 2021. In particular, the discussion deals with the coding of thyroid diseases according to ICD-10, depending on the iodine status of the population of constituent entities of the Russian Federation, as well as issues of diagnosis and treatment, such as «verification» of goiter detected by palpation, or treatment of the vast majority of children, adolescents and adults with potassium iodide. The obstacles to the epidemiological assessment of the iodine status of the population when examining schoolchildren are discussed separately, in connection with the introduction in 2020 of the new regulation, which requires the mandatory use of iodized salt for cooking in school canteens throughout the country.

The urgency of the problem of endocrine ophthalmopathy (EOP) is currently in no doubt. This is due to the fact that relatively recently methods of objective assessment of the state of the eyeball and orbital tissues using ultrasound (ultrasound), computed tomography (CT) and magnetic resonance imaging (MRI) have appeared. At the same time, the etiology and pathogenesis of EOP are not well understood, which undoubtedly affects the validity and effectiveness of various treatment methods.

The territory of Serbia has been long known to be an iodine de­ficiency area. The surveys conducted in the past 50 years have shown that iodine deficiency disorders ranged from small goiters to endemic cretinism. The iodine deficiency control program has been implemented in Serbia since 1951, in so doing, the salt con­centration of iodine (as potassium iodide) has been gradually in­creased and at present it is 20 mg/kg. Just in the mid- 1960s, io­dine prophylaxis led to cessation of new cases of cretinism and large goiters.This survey was undertaken to determine the iodine provision in Serbia. The survey was conducted in accordance with the WHO, UNICEF, and ICCIDD guidelines and it covered 4598 school­children aged 7 to 15 years from the urban and rural areas of 44 municipalities of Central Serbia and Vojvodina. Among all the examinees, the detection rate of the enlarged thyroid was 2.35% (as evidenced by ultrasound study) and the median urinary io­dine concentration was 158 μg/l. The findings suggest that iodine deficiency has been completely eliminated in Serbia due to the ef­fective program of the overall dietary salt iodination.

The article is devoted to the salt iodination is an effective way of liquidation of iodine-deficient diseases in Russia

The article is presented in the form of comments on E. P. Kasatkina’s paper offered for discussion: "Diffuse Nontoxic Goiter. Problems in Classification and Taxonomy".

The article is devoted to the total iodination of table salt for prevention of iodine deficiency diseases.

Regular (for 5 years) addition of salt iodinated with potassium iodinate to diets of children living in a region with moderate iodine deficiency normalized iodine content in the organism, decreased the incidence of goiter from 22.6 to 7.3% (according to ultrasonic data), and prevented an increase in the incidence of goiter during the prepubertal period. Evaluation of the size of goiter in screening examinations by palpation using О. V. Nikolaev’s classification leads to hyperdiagnosis (67%>), while palpation in combination with WHO classification results in hypodiagnosis of goiter (47%). Palpation of the thyroid with WHO classification is recommended as the main screening method; such a combination of methods results in a lower incidence of erroneous diagnoses (22%) than with Nikolaev's classification (56%). The level of serum TTH did not depend on iodine prophylaxis and was normal.

Approaches to diagnosis and treatment of endocrinoophthalmopathy practiced by the leading endocrinologists in Russia are analyzed. The interviews were carried out using questionnaire suggested by Research Group of European Thyroidology Association for a similar study in Europe in 1998. The data of the European and Russian studies are compared.

Endocrinological and cardiological parameters were assessed in coronary patients with nodular euthyroid goiter before and during treatment in order to define the optimal protocols of L-thyroxin therapy. Ultrasonic examination of the thyroid, fine needle puncture biopsy and cytological analysis of biopsy specimens, measurements of thyrotropic hormone, electrocardiography, and high resolution electrocardiography were carried out. The results helped distinguish the cardiological criteria for decreasing the dose of L-thyroxin or its discontinuation in coronary patients with nodular goiter and define the indications for such therapy in this patient population. Therapy with L-thyroxin is justified in the above patient population only on condition of monitoring the cardiovascular status. Therefore, the presence of coronary disease or its risk factors in a patient with nodular colloid proliferating goiter is not a contraindication preventing thyroxin therapy in adequate doses.

Iodination of foodstuffs is one basic trend in prevention of iodine deficit and diseases caused by it. The production of iodine salt is rather expensive, and hence, another highly prevalent foodstuff was chosen as "iodine carrier": bread. Bread is traditional food in Russia and its consumption is stable throughout the year. Bread baking is centralized in the majority of regions of our country. It is manufactured at rather large bakeries and delivered even to the most faraway regions. In order to solve the practical problems of baking iodinated bread, a pilot experiment was carried out in 1993-1995 in the Pavlovsky Posad district near Moscow (a region with moderate and slight iodine deficiency). The experiment was sponsored by the UNICEF (UN Childhood Foundation) and included development of the formula of bread iodination and assessment of this method of iodine prophylaxis. According to the proposed formula, 60 mg of potassium iodide is to be added per 100 g of flour; such a dose covers the daily requirement of an organism in iodine, provided 500 g of bread is consumed daily. The efficacy of iodinated bread was assessed from the time course of renal excretion of iodine and incidence of thyroid enlargement in 162 schoolchildren aged 7 to 14 at a boarding school in the town of Pavlovsky Posad, who were given 300 g of bread daily, and in 178 schoolchildren aged 9 to 11 living in the rural regions, eating about 100 g daily. After 3 months the median level of urinary iodine increased from 4.8 to 12.6 pg% in town and from 3.0 to 6.2 pg% in the country. After 9 months the levels of urinary excretion of iodine were the same, moreover, the incidence of thyroid enlargement decreased in both groups. Hence, the tasks of pilot experiment were fulfilled: a method for bread iodination has been developed and introduced at bakeries and its efficacy in normalization of iodine supply validated.

Thyroxine is one of the 13 most commonly prescribed drugs in the United States. Thyroxine is even more frequently prescribed to patients in several countries of Western Europe, where, due to iodine deficiency, there is a high prevalence of thyroid diseases. Indication for the use of thyroxine is either conventional replacement therapy in patients with hypothyroidism, or blocking the secretion of thyroid stimulating hormone (TSH) in patients with nodular goiter or after surgery for thyroid cancer. Hypothyroidism is a common disease: according to foreign authors, from 1.5 to 2% of women and about 0.2% of men suffer from it. Among people over 60, the prevalence of hypothyroidism is even higher: up to 6% of women and 2.5% of men have a TSH level that is 2 times higher than the upper limit of normal. According to foreign studies conducted in areas without iodine deficiency (UK), thyroid nodules are found in 0.8% of men and 5% of women, and the frequency of nodes increases after 45 years. In areas with iodine deficiency in the biosphere, which includes the vast majority of the territory of Russia, the frequency of nodular goiter in women of reproductive age reaches 10% or more. Thyroid cancer is the most common endocrine localization of malignant tumors. In 1984, 10,000 new cases of thyroid cancer were reported in the United States. For a long time, the selection of thyroxine doses for substitution and suppressive therapy was purely empirical and was based mainly on clinical signs: dynamics of mass, pulse, disappearance of myxedema, etc. At present, there are objective methods for controlling the thyroxine dose.

Thyroid cancer accounts for 1 - 1.5% of all malignant neoplasms. In recent years, there has been a trend towards an increase in the prevalence of this disease. On the one hand, the frequency of detection of thyroid cancer is associated with the introduction of a number of modern methods of examining patients and the increased oncological alertness of doctors. On the other hand, there is evidence of an increase in the incidence of thyroid cancer associated with an unfavorable environmental situation. An example of this is an increase in the frequency of thyroid damage in people exposed to radiation after the accident at the Chernobyl nuclear power plant. There is evidence that in Japan, thyroid cancer is detected 10 times more often among the population that has undergone nuclear bombing than among other residents of the country. Exogenous risk factors include external x-ray irradiation, previously carried out for medical purposes for various benign and non-tumor diseases of the head and neck. It is believed that exogenous factors are able to more or less affect the thyroid gland and cause a number of molecular changes in it that lead to the development of cancer. The purpose of this review was to summarize the current knowledge of the molecular aspects of thyroid cancer.

Lipiodol, an iodinated oil preparation, is used in many regions of the world characterized by severe iodine defficiency. The aim of this research was to assess the efficacy of this preparation in regions with slight and medium iodine insufficiency. A single dose of lipidol containing 200 mg iodine was administered to children aged 7 to 14 living in a region with moderate iodine deficiency, 452 of these living in town and 335 in the country. According to volumetry, the incidence of thyroid enlargement varied from 43 to 61% for different age groups and was reliably higher (p

Prolactin secretion (PRL) is under complex neuroendocrine control. in which factors of various nature are involved: neurotransmitters, biologically active neuropeptides, as well as hormones of peripheral endocrine glands. However, the dominant role belongs to dopamine, which is the most important of endogenous prolactin inhibiting substances. Convincing evidence of this was obtained after the discovery and study of the tuberoinfundibular dopaminergic system of the hypothalamus, which is a part of a complex neuroendocrine system for regulating the secretion of PRL.

Highly sensitive methods for determining the level of TSH, carried out using test kits of the second and third generation, make it possible to differentiate with high accuracy the normal and subnormal levels of TSH in the blood and are currently widely used to examine patients with thyroid pathology. These methods have been used for a long time in clinical practice in the United States of America, and recently they are also increasingly used in Russia. The level of TSH below normal values ​​is determined in almost all cases of hyperthyroidism (with the exception of cases of TSH-secreting pituitary adenoma or resistance of the pituitary to thyroid hormones), which makes it possible to do without additional testing with tyroliberin (TRH). Methods for determining second generation TSH usually have a lower sensitivity limit of about 0.1 mU/L. When using the third generation methods, it is possible to accurately determine the level of TSH up to 0.01 mU/L. The fourth generation methods, which are still under development, will have a lower limit of determination of 0.001 mU/L, but they are unlikely to be used for routine clinical studies in the near future. At the Endocrinology Research Center of the Russian Academy of Medical Sciences in Moscow, third-generation methods are currently being used for routine clinical research (the Amerlight system, produced in Russia by the Amerkard joint venture). In addition to this system, other test systems of both domestic and foreign production are also available in Russia. In the USA, methods for determining TTG of the second and third generation are used. Third-generation systems are noticeably more expensive than second-generation systems. Given that in most patients with hyperthyroidism, the TSH level is in the range of less than 0.1 mU/L, methods for determining the third generation are more preferable. In general, the normal level of TSH in the blood of individuals in a state of euthyroidism is from 0.5 to 5.0 mU/L, although there are some interlaboratory differences in the standards for the level of TSH.

The efficiency of therapy with a combined thyroxin-iodine drug and monotherapy with thyroxin was compared in patients with diffuse nontoxic goiter (DNG), and the effect of iodine intake was evaluated. The study was carried out in an outpatient setting by the double blind method in 46 women aged 18-50 years with DNG: 22 were treated by the combined drug (TI) containing 100 pg L-thyroxin and 100 pg potassium iodide per tablet (lodthyrox, Merck KGaA) and 24 were treated by thyroxin (T) in a dose of 100 pg (Euthyrox, Merck KGaA). The treatment was administeredfor 1 year. A year after this treatment, 15 women were treated with iodinated oil (IO) (lipidol capsules, Guerbet) containing 380 mg iodine. Thyroid volume, concentrations of intrathyroid stable iodine (ISI), pituitary thyrotropic hormone, free triiodothyronin and thyroxin, and antibodies to thyroglobulin and thyroid peroxidase in the blood were evaluated in all women before and during treatment. Therapy with T and TI equally decreased the size of the thyroid in DNG. ISI concentration decreased during TI treatment less than during monotherapy. Thyroid volume increased to the pre-treatment size 12 months after therapy with T or TI was discontinued, while ISI concentration remained lowered. Administration of IO led to a decrease in the thyroid size, less pronounced than during T or TI treatment, and to an increase in ISI concentration.

Seventy-six case histories of patients operated on at Surgical Department of Endocrinology Research Center of the Russian Academy of Medical Sciences in 1992-1993 were analyzed in order to evaluate the remote results of surgical treatment of diffuse toxic goiter (DTG) and potentialities of their predicting before surgery. The following factors were analyzed: age by the moment of disease manifestation, sex, initial doses of thyrostatics, duration of antithyroid therapy, thyroid function by the moment of operation, volume of the gland, indications for surgery, and scope of intervention. Thyroid function at different terms after surgical treatment was assessed by clinical data and levels of TTH and free T4. Five years after operation for DTG, 26.6%) patients were in a state of euthyrosis, 68.2%) in hypothyrosis, and 5.2%) patients developed relapses. No relationships were detected between the size and function of the thyroid before surgery, presence of endocrine ophthalmopathy, and thyroid function in remote period after surgery. The risk of postoperative hypothyrosis in DTG is higher in patients treated with thyrostatics for a long time and in elderly subjects.

Intrathyroid iodine level was measured in 126 patients with different thyroid tumours in Russia and in 37 ones in the USA by X-ray fluorescent analysis in vitro. A decrease of intrathyroid iodine concentration was found to be associated with a stepwise loss of differentiation of thyroid tumours. In colloid goitre tissue from Russia, the intrathyroid level of iodine was increased. It was markedly increased in microfollicular adenomas and colloid goitre tissue from American patients, which fact may reflect a higher iodine supply in the USA. X-Ray fluorescent analysis together with clinical studies may be used in preoperative examinations of patients with thyroid nodules.

The ultrasonic picture and volume of the thyroid, concentrations of intrathyroid stable iodine, total amount of stable iodine, scintigraphy of the organ, blood concentrations of basal TTH, fгее T4 and T3, antibodies to thyroglobulin, and microsomal fraction were studied in 77 patients (69 women and 8 men) with diffuse nontoxic goiter and 37 controls (18 women and 19 men) aged 18 to 50 without enlargement or signs of impairment of the function of the thyroid. Diffuse nontoxic goiter was found to be associated with increase of the thyroid volume, concentrations of intrathyroid stable iodine and total amount of stable iodine, and TTH, and a decreased concentration of T4. A deficit of intrathyroid stable iodine and of T3 in the blood was revealed in 20% of women with antibodies to thyroglobulin and microsomal fraction in the blood, in comparison with patients who had no antibodies to thyroglobulin and microsomal fraction. A reduced concentration of intrathyroid stable iodine in control women was attended by the presence of antibodies to thyroglobulin and/or microsomal fraction and indirect ultrasonic signs of autoimmune pathology of the thyroid. These results permit a conclusion that iodine measurements directly in the thyroid using noninvasive x-ray fluorescent analysis is a sensitive and informative additional method for the diagnosis of thyroid abnormalities.

The article is devoted to the clinical recommendations of the Russian Association of Endocrinologists for the diagnosis and treatment of autoimmune thyroiditis in adults