Six Air Pollutants Associated With Increased Risk of Thyroid Nodules: A Study of 4.9 Million Chinese Adults

BackgroundThyroid nodules has become a significant public health issue worldwide with a rapidly increasing prevalence. However, its association with outdoor air pollution remains poorly understood. We aim to investigate the relationship between six outdoor air pollutants (PM2.5, PM10, NO2, SO2, CO, and O3) and the risk of thyroid nodules.MethodsWe utilized a database including 4,920,536 participants who attended the annual physical examinations in the Meinian HealthCare Screening Center in 157 Chinese cities in 2017. City-specific concentrations of six pollutants (PM2.5, PM10, NO2, SO2, CO, and O3) from 2015 to 2017 were estimated based on the China’s National Urban Air Quality Real Time Publishing Platform. Thyroid nodule was measured with ultrasound. Multivariable Logistic regression was used to examine the associations between air pollutants and thyroid nodules with adjustment for age, sex, education, smoking, body mass index, fasting blood glucose, triglyceride, low density lipoprotein cholesterol, high density lipoprotein cholesterol, urine iodine, gross domestic product, and thyroid stimulating hormone. We conducted stratified analyses to investigate potential effect modification by sex, age, and urine iodine groups.ResultsApproximately 38% of the participants (1,869,742) were diagnosed with thyroid nodules. Each of the six air pollutants was significantly and linearly associated with the risk for thyroid nodules. The adjusted odds ratios [95% CI] for every increase of 10 μg/m3 for PM2.5, PM10, NO2, SO2, and O3 were 1.062 [1.061, 1.064], 1.04 [1.03, 1.04], 1.10 [1.09, 1.10], 1.11 [1.11, 1.12], and 1.151 [1.149, 1.154], respectively; The odds ratio for each increase of 1 mg/m3 for CO was 1.50 [1.49 to 1.52]. Furthermore, these associations were significantly higher in the participants who were men, younger, or having lower urine iodine level (p <0.001).ConclusionThe six air pollutants may contribute to the high prevalence of thyroid nodules in China.

Insufficient Iodine Level in Urine among Children of a Secondary School: A Descriptive Cross-sectional Study

Introduction: Iodine deficiency disorders are common endocrinopathies in Nepal. Children are at risk for iodine deficiency disorders. Irreversible mental retardation and brain damage in children are the devastating disorders lead by iodine deficiency. Therefore, the main objective of the study was to find out the prevalence of insufficient iodine level among the children of a secondary school. Methods: This descriptive cross-sectional study was conducted in urine from April 2019 to July 2019 after obtaining ethical approval from Nepal Health Research Council (Registration number: 802/2018). Forty-six urine samples were collected from school children for iodine estimation. Convenience sampling was done. Data were entered into Statistical Package for the Social Science version 21 and descriptive analyses were done. Point estimate at 95% confidence interval was calculated along with frequency and proportion for binary data. Results: Among the 46 students, majority 36 (78.30%) (95% Confidence Interval= 66.30-90.21) of the school children had insufficient urine iodine level. Among 36 salt samples collected from school children with low urine iodine level, 8 (22.2%) salt samples had iodine less than 15ppm. Conclusions: Iodine estimation revealed a very high percentage of urine samples containing insufficient levels of iodine is similar as compared to studies done in similar settings. Hence, the school children were at risk of iodine deficiency disorders. Iodine deficiency disorders prevention programs should be priority intervention based on available evidence.

Effect of TSH stimulation protocols on adequacy of low-iodine diet for radioiodine administration

Low-iodine diet (LID) is a crucial preparation for radioactive iodine (RAI) treatment or scan in thyroid cancer. The aim of this study is to analyze the influence of thyroid stimulating hormone (TSH) stimulation protocols and other clinical factors on LID adequacy. Thyroid cancer patients who underwent LID for RAI scan or treatment were retrospectively analyzed. Patients were guided to have LID for 2 weeks before RAI administration and urine iodine/creatinine ratio (UICR, μg/g Cr) was measured. TSH stimulation was conducted using either thyroid hormone withdrawal (THW) or recombinant human TSH (rhTSH) injection. Adequacy of LID was classified by UICR as ‘excellent (< 50)’, ‘adequate (50–100)’, ‘inadequate (101–250)’ and ‘poor (> 250)’. A total of 1715 UICR measurements from 1054 patients were analyzed. UICR was significantly higher in case of rhTSH use than THW (72.4 ± 48.1 vs. 29.9 ± 45.8 μg/g Cr, P < 0.001). In patients who underwent LID twice using both TSH stimulation protocols alternately, UICR was higher in case of rhTSH than THW regardless of the order of method. Among clinical factors, female, old-age, and the first LID were significant factors to show higher UICR. Although the adequacy of LID was ‘adequate’ or ‘excellent’ in most patients, multivariate analysis demonstrated that THW method, male, young age, and prior LID-experience were significant determinants for achieving ‘excellent’ adequacy of LID. In conclusion, UICR was higher and the proportion of ‘excellent’ LID adequacy was lower with rhTSH than with THW. UICR was higher also in women, old-age, and LID-naïve patients. Further researches are required to suggest effective methods to reduce body iodine pool in case of rhTSH use and to validate the efficacy of such methods on outcomes of RAI treatment.

Thyroid Peroxidase Antibodies as a Marker of Iodine Status in Healthy Euthyroid Women in First Trimester of Pregnancy Visiting a Tertiary Care Hospital in Raipur, India

BACKGROUND The importance of adequate iodine status in pregnancy is undoubted as its deficiency is associated with adverse pregnancy outcomes for the mother as well as the foetus and neonate. Although median urine iodine concentration can assess iodine status of the population but not at an individual level. The purpose of this study was to assess the nutritional status of iodine and identify its effects on thyroid function during the first trimester of pregnancy. METHODS The study was carried out on 341 euthyroid healthy pregnant women using urine iodine concentration and other parameters of thyroid panel at a tertiary care hospital. RESULTS Median (interquartile range) urine iodine concentration and thyroid stimulating hormone (TSH) were 227.37 (161.7, 343.86) μg / L and 1.8 (1.1, 2.7) mIU / L respectively and Mean ± SD of free thyroxine and thyroid peroxidase antibodies were 14.53 ± 2.02 pmol / L and 38.23 ± 9.29 kIU / L respectively. Only thyroid peroxidase antibodies showed significant difference across groups with different iodine status. A positive correlation of urine iodine concentration (UIC) with thyroid peroxidase antibodies was observed (r = 0.137, P = 0.011). Multiple regression analysis revealed that thyroid peroxidase antibodies can serve as an independent predictor of iodine status in the presence of normal levels of TSH and FT4 (t - 3.063, CI; 0.880, 4.038, P = 0.002). CONCLUSIONS Thyroid peroxidase antibodies progressed positively with increase in urine iodine concentration indicating its role as a marker of iodine nutritional status and for early identification of women who can develop autoimmune thyroiditis resulting in hypothyroidism even prior to elevation of thyroid stimulating hormone levels. KEY WORDS Anti-TPO Ab, Free Thyroxine, Thyroid Stimulating Hormone, Urine Iodine Concentration

Construction of a Nomogram Model to Predict The Risk of Hypothyroidism in Patients With Thyroid Nodule Caused by Environmental Iodine and Fluorine

Background: Patients with thyroid nodules may be complicated by hypothyroidism. However, effective means to predict thyroid-stimulating hormone (TSH) elevation in patients with thyroid nodules are currently lacking. Therefore, the research team recruited some patients with thyroid nodules to explore the relationship between TSH, environmental iodine, and fluoride and the development of thyroid nodules, and to draw a Nomogram in order to provide guidance for predicting hypothyroidism in patients with thyroid nodules.Methods: The subjects were from 313 patients with thyroid nodules in different areas of iodine and fluoride, with 71 men and 242 women. The content of TSH in serum of thyroid nodule patients was determined by electrochemical luminescence method. The iodine content in drinking water and urine was determined by arsenic-cerium catalytic spectrophotometry. Fluoride in drinking water and urine was determined by fluoride ion selective electrode method. Univariate analysis, Lasso regression analysis and multiple factor Logistic regression analysis were used to screen the variables included in the Nomogram model. And the corresponding Nomogram model was constructed. ROC curve was drawn and repeated Bootstrap self-sampling method was used to test model differentiation.Results: There were 53 patients with elevated serum TSH and 256 patients with normal thyroid nodule. Multivariate logistic regression analysis shows that urine iodine（Odds Ratio[OR]=1.001, 95% confidence interval [95%CI]:1.001～1.002, P=0.01） and gender (OR=3.328, 95% CI:1.256～8.819, P=0.079) are independent risk factors raised by serum TSH. And drinking water fluoride（OR=1.990, 95% CI:0.924～4.289, P=0.079）is a critical factor. Based on these risk factors, the predictive model and nomogram of serum TSH elevation in patients with thyroid nodule were constructed. The area under the ROC curve was 0.678 (P<0.001), confirming Nomogram's predictive potential. The calibration diagram of the Nomogram prediction model shows that the predicted values are in good agreement with the observed values.Conclusion: Gender, urine iodine and drinking water fluoride of thyroid nodules are independent influencing factors for the rise of serum TSH. The Nomogram can become a predictive accuracy and differentiation.