[Association between preoperative cholecalciferol therapy and hypocalcemia after parathyroidectomy in patients with primary hyperparathyroidism].

BACKGROUND: Primary hyperparathyroidism (PHPT) is a endocrine disorder characterized by excessive secretion of parathyroid hormone (PTH) from parathyroid gland tumors. Parathyroidectomy (PTE) is the main treatment for PHPT, but it can lead to hypocalcemia in up to 46% of cases. Hypocalcemia is associated with seizures and life-threatening cardiac arrhythmias, and vitamin D deficiency can exacerbate PHPT severity and contribute to «hungry bones syndrome,¼ resulting in severe and persistent postoperative hypocalcemia. AIM: To evaluate the association and determine the strength of the relationship between preoperative cholecalciferol therapy and the occurrence of hypocalcemia within 1-3 days after PTE in patients with PHPT. MATERIALS AND METHODS: The study was conducted at the Endocrinology Research Centre, during the periods of 1993-2010 and 2017-2020. The inclusion criteria consisted of patients diagnosed with PHPT who required PTE, had a serum 25-hydroxyvitamin D (25(OH)D) level below 20 ng/mL, and a serum total calcium level below 3 mmol/L. The exclusion criterion was the use of medications that affect calcium-phosphorus metabolism, including cinacalcet, denosumab, or bisphosphonates, either as monotherapy or as part of combination therapy. RESULTS: There were 117 patients, including 110 (94%) females and 7 (6%) males. The median age and interquartile range were 58 [49; 65] years. Among the participants, 21 (18%) received cholecalciferol supplementation for a duration of 2 weeks to 2 months prior to PTE, aiming to address vitamin D deficiency. The remaining 96 (82%) participants did not receive -cholecalciferol supplementation. Both groups, i.e., participants receiving cholecalciferol and those who did not, were similar in terms of anthropometric factors (sex and age at the time of surgery), preoperative clinical characteristics (BMD decrease), and laboratory parameters (PTH, total calcium, phosphorus, ALP, OC, CTX-1, and 25(OH)D levels). The occurrence of postoperative hypocalcemia was significantly lower in participants who received cholecalciferol supplementation (10% vs. 63%, p<0,001, FET2). Cholecalciferol intake showed a negative association with hypocalcemia development (RR=0,15, 95% CI (0,03; 0,51)). CONCLUSION: Preoperative cholecalciferol supplementation for 2 weeks to 2 months before PTE reduces the risk of postoperative hypocalcemia in patients with PHPT by 2-33 times.

[Comparative analysis of bone complications/manifestations in sporadic and MEN1-related primary hyperparathyroidism].

BACKGROUND: Multiple endocrine neoplasia type 1 (MEN1) - is a rare syndrome with an autosomal dominant inheritance pattern caused by a mutation in the tumor suppressor gene (MEN1). Parathyroid involvement is the most common MEN1 manifestation resulting in primary hyperparathyroidism (mPHPT). Data on the prevalence and structure of bone disease in mPHPT compared to sporadic one (sPHPT) are often incomplete and contradictory. AIM: The purpose of this study was to compare the severity of bone involvement between mPHPT and sPHPT. MATERIALS AND METHODS: A single-center retrospective study was conducted among young patients in the active phase of PHPT and without prior parathyroidectomy in anamnesis. The analysis included the main parameters of calcium-phosphorus metabolism, bone remodeling markers, as well as an assessment of disease complications. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DXA) at sites of lumbar spine, femur and radius. Trabecular bone score (TBS) was applied to estimate trabecular microarchitecture. All patients included in the study underwent genetic testing. RESULTS: Group 1 (mPHPT) included 26 patients, and group 2 (sSHPT) included 30 age-matched patients: the median age in group 1 was 34.5 years [25; 39], in group 2 - 30.5 years [28; 36], (p=0.439, U-test). Within group 1, the subgroup 1A (n=21) was formed with patients without other hormone-produced neuroendocrine neoplasms (NEN) in the gastrointestinal tract (GI) and the anterior pituitary gland. The duration of PHPT was comparable in both groups: mPHPT - 1 year [0; 3] versus sPHPT - 1 year [0; 1], (p=0.533, U-test). There were no differences in the main parameters of calcium-phosphorus metabolism, as well as in the prevalence of kidney complications. In the mPHPT group, bone abnormalities were observed significantly more often compared to sPHPT: 54 vs 10% (p=<0.001; F-test). Statistically significant differences were revealed both in BMD and in Z-score values of the femoral neck and total hip, which were lower in the mPHPT group. These differences remained significant when comparing subgroup 1A with sPHPT. CONCLUSION: MEN1-associated PHPT may be accompanied by a more severe decrease in BMD in the femoral neck and total hip compared to sPHPT regardless of the other hormone-producing NEN. Clarifying the role of mutation in the MEN1 gene in these processes requires further study.

[Predicting the presence of MEN1 gene mutation based on the clinical phenotype of patients with primary hyperparathyroidism].

BACKGROUND: Timely referral of patients for genetic testing to rule out MEN1-associated primary PHPT is important factor in determining treatment strategy and prognosis. In the context of the limited availability of genetic testing, the search for clinical markers indicative of MEN1 gene mutations remains an extremely relevant task. AIM: To determine the diagnostic value of clinical features of primary PHPT in young patients for predicting the presence of MEN1 gene mutations. MATERIALS AND METHODS: A single-center, prospective study was conducted at the Endocrinology Research Centre, involving 273 patients with PHPT in the period 2015-2022. Based on the results of genetic and laboratory tests, patients were divided into three groups: those with MEN1 gene mutations (MEN+ group, n=71), those without MEN1 gene mutations - isolated sporadic PHPT (MEN- group, n=158), and patients with PHPT and associated endocrine gland disorders - MEN-1 syndrome phenocopies (PHEN group, n=32). Subgroups of patients younger than 40 years of age were also identified. Comparative analysis was performed among the independent groups and subgroups, and logistic regression analysis was used to develop a mathematical model for predicting the probability of the presence of MEN1 gene mutation. RESULTS: Patients in the MEN+ and MEN- groups were comparable by gender and age at manifestation, as well as calcium-phosphorus metabolism parameters and PHPT complications. In the PHEN group, PHPT manifested at older age compared to the other groups (p<0.001 for all), with lower total calcium levels and a trend toward lower iPTH concentrations. The MEN+ group had a significantly higher frequency of multiglandular parathyroid (PG) involvement, PHPT recurrence, and positive family history compared to the MEN- and PHEN groups. Histologically, adenomas predominated in the PHEN and MEN- groups (92% and 94%, respectively), whereas hyperplasia of PGs were more common in the MEN+ group (49%). None of the PHEN patients had all three «classic¼ components of the MEN-1 syndrome, and the clinical course of PHPT was similar to that of the MEN- group. These differences were also observed in the subgroups of patients younger than 40 years, which formed the basis for the development of a mathematical model. The logistic regression equation for predicting the probability of the presence of the MEN1 gene mutation included eight predictors, with a diagnostic sensitivity of 96% and specificity of 98%. CONCLUSION: Based on the analysis performed, eight hereditary predictors of PHPT within the MEN-1 syndrome were identified. A mathematical model was developed to predict the presence of the MEN1 gene mutation in patients, which demonstrated high classification performance on the training dataset. Further refinement of the model will help improve the quality of medical care for patients with PHPT.

[Clinical and immunological predictors of Graves' orbitopathy after radioiodine therapy of Graves' disease].

BACKGROUND: Data on the effect of 131I on the course of Graves' orbitopathy (GO) are contradictory. A number of studies indicate a deterioration in the course of GO against the background of RAIT, in other studies such a connection has not been established. Cytokines that regulate inflammation could potentially be biomarkers for assessing GO activity and predicting the course of GO after RAIT. AIM: The purpose of this study was to evaluate the dynamics of eye symptoms and analyze immunological parameters: cytokine TGF-ß1 and cytokine receptors: sTNFα-R1, sTNFα-R2, sIL-2R, sIL-6R over time after RAIT, as possible predictors of GO activation. MATERIALS AND METHODS: The study included 59 patients (118 orbits) with GD in the state of euthyroidism and subclinical hyperthyroidism and low active and inactive GO, aimed at conducting RAIT. Concentrations of cytokine TGF-ß1, sTNFα-RI and sTNFα-R2, sIL-2R, sIL-6R, TSH receptor antibodies (rTSH-Ab), free thyroxine (FT4) and free triiodothyronine (FT3), -thyroid-stimulating hormone (TSH) in the blood serum were determined. Ultrasound examination of the thyroid gland, multispiral computed tomography (MSCT)/magnetic resonance imaging (MRI) of the orbits was performed. The examination was carried out 3, 6, 12 months after the RAIT. RESULTS: The deterioration of the course of the GO (1-2 points according to CAS) was noted after 3 months. (32.5%) and to a lesser degree after 6 and 12 months (13.2% and 8.45%, respectively). Dynamics were not noted, approximately, in the same number of patients (40.5%, 41.5%, 45.8%, respectively). An improvement in the course of the GO was noted after 6 and 12 months (45.3, 45.8, respectively). After 3 and 6 months, the achievement of hypothyroidism and a significant increase in the level of rTSH-Ab were noted. In the analysis of cytokines and their receptors a significant decrease in the level of TGF-ß1 was noted after 3, 6 and 12 months. There was also a significant decrease in sTNF-R1 and sIL-2R at 3 and 6 months. The level of sTNFα-R2 significantly decreased 3 months after RAIT. The level of sIL-6R has not changed significantly. After 3 months in patients with positive dynamics of image intensification, the level of TGF-ß1 did not significantly change compared with the level before RAIT, in patients with worsening of the course of GO or without dynamics, the level of TGF-ß1 significantly decreased. After 6 months, there was the same trend, not reaching statistical significance. The IgG4 level and the IgG4/IgG ratio increased to 6 and 12 months, which corresponded to an increase in diplopia index. CONCLUSION: The main limiting factor in the conduct of RAIT is the activity of the autoimmune process in the orbits. Since patients with inactive (CAS 0-2) or low activity (CAS 3-4) GO were referred for RAIT, there was no pronounced activation of GO after RAIT. There was a slight deterioration in the course of GO by only 1-2 points according to CAS after 3 months. (32.5%) and to a lesser degree after 6 months (13.2%). In the study, it was found that the main predictors of the deterioration of the course of GO after RAIT are uncompensated hypothyroidism, a high level of rTSH-Ab and a decrease in the level of cytokine TGF-ß1.

[Dynamics the parameters of mineral metabolism in hospitalized patients with COVID-19, the impact of etiotropic and pathogenetic therapy].

The high prevalence of COVID-19 requires the research progress on the disease pathogenesis. There is a lot of data confirming the association between mineral metabolism and the severity of COVID-19. AIM: To study the dynamics of mineral metabolism parameters in patients with a confirmed COVID-19 at the time of hospitalization and after discharge, including the impact of etiotropic and pathogenetic therapy on them. MATERIALS AND METHODS: A single-center study of 106 patients (aged ≥18 years) with clinically or laboratory confirmed diagnosis of COVID-19 was carried out at the Endocrinology Research Centre, Moscow. Baseline biochemical parameters, including serum calcium, phosphorus, albumin, 25(OH)D, parathyroid hormone (PTH), inflammatory markers, and instrumental assessment of COVID-19 severity were performed before specific immunotherapy, as well as on 3rd and 7th days of hospitalization and before discharge. Statistical analysis was performed with Statistica 13 software (StatSoft, USA). RESULTS: On the first day, hypocalcemia (low albumin-adjusted calcium level) was detected in 40.6% of cases, the prevalence of vitamin D deficiency/insufficiency amounted to 95.3% of cases. At the same time, secondary hyperparathyroidism was identified only in 14.2% of patients. A comparative analysis of mineral metabolism during hospitalization (between 1, 3, 7 days of hospitalization and before discharge) during baricitinib treatment revealed a statistically significant increase in albumin-adjusted calcium by the end of hospitalization (p<0.001, Friedman criterion, Bonferroni correction p0=0.01). A pairwise comparison of subgroups, depending on the therapy, revealed a statistically significantly lower level of albumin-adjusted calcium on 3rd day among patients on baricitinib monotherapy or combined with tocilizumab compared with a subgroup of patients undergoing etiotropic treatment (2.16 [2.13; 2.18] mmol/l vs 2.23 [2.19; 2.28] mmol/l, p=0.002, U-test, Bonferroni correction p0=0.012). CONCLUSION: Patients with severe coronavirus infection are characterized by a high prevalence of vitamin D deficiency and hypocalcemia. Associations between calcium and saturation as well as the severity of lung lesion characterizes hypocalcemia as an important predictor of severe course and poor outcome in COVID-19. Pathogenetic therapy with baricitinib, including in combination with tocilizumab, contributes to achieve normocalcemia, but further studies are required.

[Primary bilateral macronodular adrenal hyperplasia: clinical and laboratory features].

BACKGROUND: Primary bilateral macronodular adrenal hyperplasia (PBMAH) is characterized by bilateral benign adrenocortical lesions, which in some cases lead to Cushing syndrome (CS). Due to the low detection, non-specific, erased clinical picture and slow, long-term progression, it is difficult to assess the true prevalence of PBMAH. This also leads to fairly limited literature data. A detailed analysis of biochemical, imaging parameters, the clinical presentations, in particular, an assessment of the course of comorbidities (arterial hypertension (AH), diabetes (DM), osteoporosis), is necessary to develop an algorithm for managing patients with PBMAH. AIM: Analysis of clinical and laboratory characteristics of patients with various forms of PBMAH. MATERIALS AND METHODS: A single-center, retrospective, observational, cross-sectional study was carried out. This study included 110 patients with PBMAH who got referred to the National Research Center for Endocrinology in the period from 2013-2023. We carried out comparative and correlation analysis of hormonal (plasma cortisol concentrations after 1 mg dexamethasone (1-mg DST), urinary free cortisol (СКМ), ACTH), biochemical (glycated hemoglobin), radiological data (nodular tissue volume), course of comorbidities (metabolic syndrome, DM, AH, osteoporosis) in three groups of patients: with overt CS, mild autonomous cortisol excess (MACE) and comorbid diseases, and patients with PBMAH without hormonal activity. RESULTS: Among 110 patients 79.1% were women, median age - 60 [51; 68]. The proportion of hormonally inactive forms of PBMAH was 37.3%, the overt CS and MACE was detected in 25.4 and 37.3% consequently. According to the hormonal -examination data: the cortisol level during 1-mg DST was 173.8 nmol/l [86.0; 441.0], ACTH - 3.35 pg/ml [1.00; 8.00], СКМ - 445.5 [249.0; 900.0]. Statistically significant positive moderate correlations were found between the volume of nodular tissue and the level of cortisol after PDT1 (r=0.40, p<0.001), СКМ (r=0.29, p<0.004), as well as a negative moderate correlation between the volume and the level of ACTH (r=-0.40, p<0.001). When analyzing the prevalence and clinical severity of comorbid conditions, DM was diagnosed in 22 (53.7%), AH in 36 (87.8%), obesity and osteoporosis - 23 (56%) and 3 (7.3%) patients. There was no statistically significant difference in the prevalence of CS-associated diseases among the above groups (p=0.56). CONCLUSION: PBMAH is a heterogeneous pathology with different clinical, hormonal, and imaging characteristics. A correlation was found between the volume of nodular tissue and the degree of hormonal activity of PBMAH. The obtained results emphasize the difficulty in determining clear indications for surgical treatment in the group of patients with MACE. The radicality of proposed surgical procedure should be weighed against its potential complications.

[The role of systemic immune activation in the development of thyroid dysfunction in COVID-19].

BACKGROUND: The research of cytokine-induced thyropathies in the midst of continuing coronavirus infection (COVID-19) pandemic is a very important and urgent problem. On the one hand, COVID-19 is often accompanied by a massive overproduction of cytokines, so we can expect an enhanced cytokines effects impact on the thyroid gland. On the other hand, it is possible that biological therapy with tocilizumab, which has a powerful immunosuppressive effect, plays a protective role to the development of cytokines-induced thyropathies amidst COVID-19. The results of the study should be the starting point for understanding the mechanisms of possible compromise of thyroid function during COVID-19. AIM: The primary endpoint is to assess the relationship between the levels of thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) with the inflammatory process markers. The secondary endpoint is the identification of an association between TSH, FT3 and FT4 values, and patient survival. MATERIALS AND METHODS: This retrospective, single-center study included 122 patients hospitalized at the National Medical Research Center for Endocrinology with a clinical and laboratory analysis of COVID-19 and bilateral polysegmental viral pneumonia. To assess the functional status of the thyroid gland all patients underwent observation of the TSH, FT3, FT4, antibodies to thyroid peroxidase, antibodies to the TSH receptor (AT-recTSH). The markers of the inflammatory process were assessed: interleukin-6, C-reactive protein, the degree of lung tissue damage according to multispiral computed tomography of the lungs, the percentage of blood oxygen saturation (SpO2), the treatment outcomes. RESULTS: Five (4%) patients were found with subclinical thyrotoxicosis. Serum TSH values were inversely correlated with interleukin-6 (r=-0.221; p=0.024). Analysis of the level of hospital mortality, stratified by TSH, revealed statistically significantly lower TSH values in the group of deceased patients (p=0.012). The median TSH in surviving patients was 1.34 [0.85; 1.80], for the deceased 0.44 [0.29; 0.99]. CONCLUSION: Our research shows that the trigger of thyropathies in coronavirus infection is most likely thyroid tissue damage by the proinflammatory cytokines. This study shows some specific clinical aspects regarding the clinical relevance in patients with thyrotoxicosis and COVID-19, namely, the high hospital mortality rate.

[The short test with hydrochlorothiazide in differential diagnosis between primary normocalcemic and secondary hyperparathyroidism for inpatient treatment].

BACKGROUND: Differential diagnosis between the normocalcemic primary hyperparathyroidism (nPHPT) and secondary hyperparathyroidism (SHPT) due to hypercalciuria remains a challenge. AIM: The aim of this study was to investigate the capability of short test with hydrochlorothiazide for the differential diagnosis of nPHPT and SHPT. MATERIALS AND METHODS: A retrospective study was conducted with the participation of 28 patients who underwent a functional test with thiazide diuretics during hospitalization in the Department of parathyroid glands pathology and mineral disorders of the Endocrinology Research Centre, Russia. Parameters of mineral metabolism were evaluated before and 3-5 days after taking hydrochlorothiazide 50 mg/day. RESULTS: According to baseline and dynamic biochemical evaluation patients were divided into 3 groups. Group 1 (n=21) included patients with confirmed PHPT, who reached hypercalcemia accompanying with an elevated level of iPTH (n=19) or an increased level of iPTH accompanying with normocalcemia (n=2). In group 1, baseline Caadj. was 2.48 mmol/l [2.47; 2.52], iPTH 107.5 pg/ml [86.8; 133.0], after short test - 2.63 mmol/l [2.59; 2.66] and 102.1 pg/ml [95,7; 124,1]. Group 2 included only one who was diagnosed with SHPT, a normal value of iPTH with concomitant normocalcemia was achieved after 4 days of hydrochlorothiazide therapy (baseline Caadj. 2.35 mmol/l, iPTH 74.5 pg/ml vs at 2.27 mmol/l and 50.7 pg/ml respectively). Patients with doubtful results of the test entered in group 3 (n=6), they did not achieve significant changes in the calcium and iPTH levels, so it was recommended to continue the test on an outpatient basis (baseline Caadj. 2.39 mmol/l [2.33;2.45], iPTH 97.0 pg/ml [83.1;117.0]); after short test - 2.47 mmol/l [2.42; 2.48] and 91.3 pg/ml [86.9; 124.0] respectively). Groups with PHPT and SHPT and doubtful results significantly differed from each other in Caadj (р=0.003, U-test, Bonferroni correction Р0=0.006), but not in iPTH, daily calciuria, eGFR, and phosphorus. There were no significant differences in the incidence of classical complications of PHPT. CONCLUSION: The diagnosis of PHPT was confirmed in 21/28 patients 3-5 days after taking hydrochlorothiazide 50 mg/day. The obtained results are significant for the differential diagnosis in hospitalized patients with an unspecified genesis of hyperparathyroidism.

Risk factors for COVID-19 case fatality rate in people with type 1 and type 2 diabetes mellitus: A nationwide retrospective cohort study of 235,248 patients in the Russian Federation.

The aim: To study the association of demographic, clinical, and laboratory factors and the use of glucose-lowering drugs and anti-coronavirus disease (COVID-19) vaccination with the COVID-19-related case fatality rate (CFR) in diabetes mellitus (DM) patients. Methods: This study is a nationwide observational cohort study based on the data from the National Diabetes Register (NDR) that is the database containing online clinical information about the population with DM. The outcomes (death or recovery) for COVID-19 were registered in 235,248 patients with DM [type 1 diabetes mellitus (T1DM), n = 11,058; type 2 diabetes mellitus (T2DM), n = 224,190] from March 20, 2020, until November 25, 2021. The unadjusted odds ratio (OR) and 95% confidence interval (CI) were used to estimate the risk factors for CFR. Then the ranging of significant factors was performed and the most vulnerable groups of factors for the lethal outcome were chosen. Results: The CFR due to COVID-19 was 8.1% in T1DM and 15.3% in T2DM. Increased CFR was associated with the male population [OR = 1.25 (95% CI: 1.09-1.44) in T1DM and 1.18 (95% CI: 1.15-1.21) in T2DM], age ≥65 years [OR = 4.44 (95% CI: 3.75-5.24) in T1DM and 3.18 (95% CI: 3.09-3.26) in T2DM], DM duration ≥10 years [OR = 2.46 (95% CI: 2.06-2.95) in T1DM and 2.11 (95% CI: 2.06-2.16) in T2DM], body mass index (BMI) ≥30 kg/m2 [OR = 1.95 (95% CI: 1.52-2.50)] in T1DM, HbA1c ≥7% [OR = 1.35 (95% CI: 1.29-1.43)] in T2DM. The atherosclerotic cardiovascular disease (ASCVD) and chronic kidney disease (CKD) were associated with higher CFR in T1DM but not in T2DM. The pre-COVID-19 glucose-lowering therapy in T2DM was differently associated with CFR (OR): 0.61 (95% CI: 0.59-0.62) for metformin, 0.59 (95% CI: 0.57-0.61) for dipeptidyl peptidase-4 inhibitors (DPP-4 inhibitors), 0.46 (95% CI: 0.44-0.49) for sodium-glucose co-transporter-2 (SGLT2) inhibitors, 0.38 (95% CI: 0.29-0.51) for glucagon-like peptide-1 receptor agonists (arGLP-1), 1.34 (95% CI: 1.31-1.37) for sulfonylurea (SU), and 1.47 (95% CI: 1.43-1.51) for insulin. Anti-COVID-19 vaccination was associated with a lower fatality risk in both DM types: OR = 0.07 (95% CI: 0.03-0.20) in T1DM and OR = 0.19 (95% CI: 0.17-0.22) in T2DM. Conclusions: The results of our study suggest that increased COVID-19-related fatality risk in both T1DM and T2DM patients associated with the male population, older age, longer DM duration, and absence of anti-COVID-19 vaccination. In T2DM, pre-COVID-19 glucose-lowering therapy with metformin, DPP-4 inhibitors, SGLT2 inhibitors, and arGLP-1 had a positive effect on the risk of death. The most vulnerable combination of risk factors for lethal outcome in both DM types was vaccine absence + age ≥65 years + DM duration ≥10 years.

[Reference intervals of thyroidstimulating hormone in pregnant women living in the central regions of the Russian Federation].

BACKGROUND: Pregnancy is a condition with important structural and physiological changes in the thyroid gland. In this regard, experts of thyroid associations have recommended developing specific reference intervals taking into account the natural and socio-geographical characteristics of the region under study. AIM: To conduct an epidemiological analysis and evaluate TSH reference intervals in pregnant women living in the central regions of the Russian Federation with mild iodine deficiency. MATERIALS AND METHODS: We have conducted the observational multicenter cross-sectional study included 2008 healthy pregnant women at different trimesters of pregnancy, from three regions of the Russian Federation (Moscow, Ivanovo and Smolensk). We assessed the level of thyroid-stimulating hormone, antibodies to thyroid peroxidase, antibodies to serum thyroglobulin, the level of iodine concentration in the morning portion of urine (cerium arsenic method) and we have conducted a questionnaire (date birth and gestational age). Women with elevated titers of anti-TPO and/or anti-TG antibodies were excluded from the study (245 women). As a result, we assessed high and medium levels of TSH and its overestimation with iodine sufficiency in pregnant women. The results are presented using the calculation of 2.5 and 97.5 percentiles. RESULTS: We confirmed the presence of iodine deficiency in the study areas. The median concentration of iodine in the urine was: in Moscow 106 µg/l, in Ivanovo 119 µg/l, in Smolensk 134 µg/l. Pregnant women were divided into 2 groups according to iodine adequacy. In the group with optimal iodine supply, the level of TSH was 0,006-3,36 in the 1st trimester, 0,20-3,74 in the 2nd trimester, and 0,33-3,68 mIU/L in the 3rd trimester. In the group with mild iodine deficiency - in the 1st trimester it was 0,11-3,00, in the 2nd trimester 0,22-3,78, in the 3rd trimester 0,07-3,04 mIU/l. Statistical analysis of the data revealed that when comparing the level of TSH by trimester, depending on the place of residence, no statistical difference was found (p = 0,239). CONCLUSION: We obtained that the level of TSH in healthy pregnant women living in the central regions of the Russian Federation does not exceed 3.8 mIU/l in all trimesters.