Determination of Serum Thyroglobulin Concentration in Simple Diffuse Goiter Patients with Known Iodine Status

Background: Thyroglobulin (TG) seems to be a valuable indicator of thyroid function and iodine nutrition status. Aim of the study: The aim of the study was to observe the relationship between serum thyroglobulin and urinary iodine (UI) in simple diffuse goiter patients.Methods:This cross-sectional observational study was conducted at the Department of Endocrinology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. The study duration was 2 years, starting from May 2014 to March 2016. Total 87 patients with simple diffuse goiter attending the OPD Department of Endocrinology of BSMMU had been recruited as study population. A purposive sampling technique was followed for sample selection.Results:Serum thyroglobulin (ng/mL, mean±SD and median) was lowest in the age group 12-16 years (6.0±4.5, 5.16 ng/mL) followed by age>31 years (8.8±8.1, 6.16 ng/mL), whereas other age groups showed level around 13.0 and 10.0 ng/mL (p= 0.520). Mean (±SD) Urinary Iodine was not statistically different among age groups (347.4± 226.5 vs. 337.08±188.9 vs. 300.5± 95.37 vs. 337.7± 225.42 vs. 278.3± 105.7, µg/L; F 0.451, p=0.771) while median values were 325.26 vs. 355.68 vs. 325.80 vs. 338.86 and 300.90 µg/L respectively. Neither thyroglobulin (5.76±5.72 vs. 11.60± 13.50; 3.47 vs. 8.9 ng/mL, m±SD and median; p=0.294) nor Urinary Iodine (373.5± 44.5 vs. 317.2± 180.32; 378.1 vs. 308.9 µg/L, m±SD and median; p=0.450) were statistically different between the gender groups. Similarly, thyroglobulin and Urinary Iodine were also statistically similar for grade-1 and grade-2 goiter (thyroglobulin: 6.79±4.33 vs. 11.67±13.69 and 6.74 vs. 8.02 ng/mL, m±SD and median, p=0.319; Urinary Iodine: 361.33± 51.60 vs. 317.09± 182.44, 362.69 vs. 305.35 µg/L, m±SD and median, p=0.498).Conclusion:Thyroglobulin seems to have an inverse association in iodine deficiency state and positive association in over sufficient state with UI. There was no statistically significant difference of TG concentration between males and females nor between Grade-1 and Grade-2 goiter.

Urinary Iodine Concentration as an Indicator of Iodine Status and its Correlation with the Thyroid Hormones and Hemoglobin Levels in First Trimester Pregnant Women - An Exploratory Study

During pregnancy, the daily requirement of iodine increases making those most at-risk population for iodine deficiency disorders. The available confined data shows that pregnant women are iodine deficient even in iodine sufficient regions with this background the objectives of the current study were to assess the urinary iodine concentration (UIC) and evaluate the relationship between the levels of hemoglobin, UIC, and thyroid status in first-trimester pregnant women. A cross-sectional hospital-based study with a total sample size of n=110 pregnant women at the13th week of gestation in the Mysuru district was selected. The UIC, anthropometric measurements, iodine intake, and selected biochemical parameters (TSH, FT3, FT4, and Hb) were assessed. The data was analysed using SPSS (v 16.0). Spearman’s rank correlation test was used to analyse correlations. The Mann- Whitney U test was used to compare differences between groups. ANOVA was used to study the comparison of pregnancy complications with UIC and hemoglobin. The median UIC (mUIC) was 194.2 µg/L and Hb was 10.5 g/dL. Even though the mUIC was normal, around 38.2% had insufficient UIC. Significant inverse relationship between UIC and TSH (r = -0.487, p<0.001), Hb and TSH (r = -0.355, p < 0.001), and between TSH and iodine intake (r=-0.476, p<0.001) were observed. It was interesting to observe that those with insufficient UIC were found to have mild anaemia and low FT4 levels and those with excess UIC had lower TSH levels. The pregnant women in the present study were found to have the normal median urinary iodine concentration and were mildly anaemic. Increased attention among pregnant women should be focused on iodine status along with iron status and thyroid functions. Larger comparative studies need to be performed to study the impact of altered iodine status on neonatal outcomes.

Current iodine status in Japan: A cross-sectional nationwide survey of schoolchildren, 2014–2019

Context Japan has been regarded as a long-standing iodine sufficient country without iodine fortification; however, data on nationwide iodine status is lacking. Objective This study aimed to characterize the iodine status in Japan. Methods From 2014 through 2019 a nationwide school-based survey was conducted across all districts in Japan. Urinary iodine concentration (UIC), creatinine (Cr) concentration and anthropometry were assessed in healthy school-aged children (SAC) aged 6 to 12 years. Their iodine status is regarded as generally representative of the nation's iodine status. Results A total of 32,025 children participated. The overall median UIC was 269 μg/L which was within the WHO’s adequacy range. There was a regional difference in UIC values within 14 regions, and the lowest and highest median UIC were found in Tanegashima Island (209 μg/L) and Nakashibetsu, Hokkaido (1,071 μg/L), respectively. The median UIC ≥ 300 μg/L was observed in 12 out of 46 regions. By using estimated 24-h urinary iodine excretion (UIE), the prevalence of SAC exceeding the upper tolerable limit of iodine for Japanese children was from 5.2 to 13.7%. The UIC values did not change with age, BSA and BMI percentile, while the Cr concentration simultaneously increased suggesting the effect of urinary creatinine on UI/Cr and estimated 24-h UIE values. Conclusions The iodine intake of Japanese people is adequate, but in some areas it is excessive. The incidence and prevalence of thyroid disorders associated with iodine intake should be obtained especially in the areas where high amounts of iodine are consumed.

Low Urinary Iodine Concentration Is Associated with Increased Risk for Elevated Plasma Glucose in Females: An Analysis of NHANES 2011–12

Iodine intake in the US has declined in recent years. Iodine insufficiency increases the risk for inadequate thyroid hormone production and there is growing evidence that sub-clinical hypothyroidism may be disruptive to metabolic health, including insulin resistance (IR). We investigated the association between urinary iodine concentrations (UIC), a measurement of iodine status, and IR in adults. Data from 1286 US adults (≥20 years) in the NHANES 2011–2012 were analyzed. Two subgroups (low = UIC < 100 µg/L and normal = UIC ≥ 100 µg/L) were compared for markers of IR, including fasting plasma glucose (FPG) and insulin, homeostatic model assessment of insulin resistance (HOMA-IR), and glycated hemoglobin (HbA1C). Chi-square test, both linear and logistic regression models were used. In males, there were no significant associations between UIC and markers of IR; however, females with normal UIC had greater risks for elevated HOMA-IR (AOR = 0.56, 95% CI= 0.32–0.99) and HbA1C (AOR = 0.56, 95% CI = 0.34–0.90), while females with low UIC had a greater risk for FPG ≥ 5.6 mmol/L (AOR = 1.73, 95% CI = 1.09–2.72). Results only partially support our hypothesis that UIC is associated with the odds of IR in adults. The finding of an increased risk for elevated FPG, a marker of prediabetes, in female adults with low iodine status requires further investigation.

Assessment of iodofolic supplementation on thyroid function in pregnant women with iodine sufficient status and their infants in Birjand

Background: Maintaining iodine at sufficient levels is necessary throughout the pregnancy to prevent adverse outcomes in infants. This study aimed to assess iodofolic supplementation's impact on thyroid function in women at the end of the third trimesters of gestation. Methods: This case-control study was conducted on 130 pregnant women in the Birjand, east of Iran, during the period from August 2017 to February 2019. We assessed iodofolic supplementation effect in the women at the first trimesters of gestation and followed them at the end of the third trimesters and also their infants on days 3-5. Serum samples were obtained from women and infants for measuring levels of thyroid-stimulating hormone (TSH). Urinary iodine concentration (UIC) was also determined at the end of the third trimester. Results: The median serum TSH concentration in the folic acid consumed group (3.26 ± 1.91) did not significantly differ from another group (2.98 ± 1.41), (p = 0.68). There is also no considerable difference in the mean serum TSH concentration between infants born from mothers who consumed folic acid in the first trimester of pregnancy and another group (p = 0.50). The TSH concentration in all infants was below 5 µM/L. The significant difference in the mean of UIC was also not observed between pregnant women in the folic acid consumed group (188.02 ± 105.38) and iodofolic consumed group (225.77 ± 130.26), (p = 0.13). Conclusion: Iodine intake in our study was sufficient according to the WHO recommendation and idofolic supplementation was not emphasized.

Nutritional iodine status and obesity

Iodine is an essential component of the thyroid hormones, thyroxine and triiodothyronine. Its availability strictly depends on iodine content of foods, which may vary from very low to very high. Inadequate iodine intake (deficiency or excess) may affect thyroid function resulting in hypothyroidism or hyperthyroidism. Based on median urinary iodine concentrations, epidemiological criteria have been established for the categorization and monitoring of nutritional iodine status of a population (or subgroups of populations). Additional methods for iodine intake assessment include measurement of thyroid size (by thyroid palpation or ultrasonography) and of biochemical parameters, such as neonatal thyroid stimulating hormone, thyroglobulin and thyroid hormones.Recent studies carried out in overweight/obese children and adults provide evidence that body mass index (BMI) may significantly influence the above indicators, thus theoretically affecting the epidemiological evaluation of nutritional iodine status in populations.In this short review, we analyze current knowledge on the effects of overweight and obesity on indicators of adequacy and monitoring of iodine status, namely urinary iodine excretion and thyroid volume and echogenicity.Data on urinary iodine excretion in overweight/obese children are divergent, as both increased and reduced levels have been reported in overweight/obese children compared to normal-weight controls.Whether gastrointestinal surgery may affect iodine absorption and lead to iodine deficiency in patients undergoing bariatric surgery has been evaluated in a limited number of studies, which excluded iodine deficiency, thus suggesting that supplements usually recommended after bariatric surgery do not need to include iodine.Albeit limited, evidence on thyroid volume and obesity is consistent with a direct relationship between thyroid volume and BMI, irrespective of nutritional iodine status. Finally, a higher frequency of thyroid hypoechoic pattern has been described in overweight/obese children. This finding has been recently related to an increased adipocyte infiltration and thyroid parenchyma imbibition mediated by inflammatory cytokines and should be considered when the frequency of thyroid hypoechoic pattern is used as non-invasive marker to indirectly assess thyroid autoimmunity in monitoring Universal Salt Iodization programs. Further studies, specifically addressing the role of schoolchildren body mass index as a factor potentially influencing iodine intake indicators are needed.

Relationship between water iodine and children’s goiters

Excessive iodine can lead to goiters. However, the relationship between the water iodine concentration (WIC) and goiter rate (GR) is unclear. This study aims to explore the factors that influence children’s GR in areas with high WIC and analyse the threshold value of the GR increase associated with the WIC. According to the monitoring of the areas with high WIC in China in 2018–2020, a total of 54,050 children in eight high water iodine provinces were chosen. Drinking water, urine and edible salt samples of children were collected. The thyroid volume (Tvol) was measured. A generalized additive model (GAM) was used to analyse the relationship between the WIC and GR in children. Among the 54,050 children in areas with high WIC, the overall GR was 3.34%, the median of water iodine concentration (MWIC) was 127.0 µg/L, the median of urinary iodine concentration (MUIC) was 318 µg/L, and the noniodized salt coverage rate (NISCR) was 63.51%. According to the GAM analysis results, water iodine and urinary iodine are factors that influence the Tvol and GR, while the NISCR affects only the GR. When the WIC was more than 420 µg/L or the urinary iodine concentration (UIC) was more than 800 µg/L, the GR increased rapidly. When the NISCR reached more than 85%, the GR was the lowest. Thus, in areas with high WIC, WIC more than 420µg/L may increase the risk of goiter, and the NISCR should be increased to over 85% to avoid goiters in children.

HPLC Analysis of the Urinary Iodine Concentration in Pregnant Women

Iodine is an essential component for fetal neurodevelopment and maternal thyroid function. Urine iodine is the most widely used indicator of iodine status. In this study, a novel validated ion-pair HPLC–UV method was developed to measure iodine concentration in clinical samples. A sodium thiosulfate solution was added to the urine sample to convert the total free iodine to iodide. Chromatographic separation was achieved in a Pursuit XRs C8 column. The mobile phase consisted of acetonitrile and a water phase containing 18-crown-6-ether, octylamine and sodium dihydrogen phosphate. Validation parameters, such as accuracy, precision, limits of detection and quantification, linearity and stability, were determined. Urinary samples from pregnant women were used to complete the validation and confirm the method’s applicability. In the studied population of 93 pregnant women, the median UIC was lower in the group without iodine supplementation (117 µg/L, confidence interval (%CI): 95; 138) than in the supplement group (133 µg/L, %CI: 109; 157). In conclusion, the newly established ion-pair HPLC–UV method was adequately precise, accurate and fulfilled validation the criteria for analyzing compounds in biological fluids. The method is less complicated and expensive than other frequently used assays and permits the identification of the iodine-deficient subjects.

High Iodine Urinary Concentration Is Associated with High TSH Levels but Not with Nutrition Status in Schoolchildren of Northeastern Mexico

According to the Iodine Global Network, Mexico is considered a country with adequate national iodine intake (297 mg/L), but some regions have not been studied. We aimed to evaluate urinary iodine concentration (UIC) and its association with thyroid stimulating hormone (TSH) levels and the nutritional status in 307 children (aged 5 to 11 years) from three elementary schools of Monterrey, northern Mexico. UIC in spot urine samples and capillary TSH levels were measured to assess thyroid function, in addition to weight, height, body mass index (BMI), and waist circumference (WC). We found a median UIC of 442 mg/L and a significant association between UIC and TSH levels by logistic regression when data were adjusted for (1) age and sex; (2) age, sex, and WC; and (3) age, sex, and weight status. UIC values were higher in 7-year-old children compared to 11-year-old children. High prevalences of overweight/obesity (41%) and WC >90 pctl (22%) were observed. This study identified higher UIC levels in children than those previously reported in the country. The UIC showed a positive and significant correlation between TSH levels in the three models evaluated. More studies are needed to assess the causes and possible outcomes of high UIC levels.

Nationwide Representative Survey of Dietary Iodine Intake and Urinary Excretion in Postpartum Korean Women

Iodine is an essential component of thyroid hormones, but excessive iodine intake can lead to thyroid dysfunction. Traditionally, Korean mothers consume brown seaweed soup (miyeokguk), a high source of iodine, after childbirth. There is controversy regarding the effects of excessive postpartum iodine intake on the health of mothers and infants. Thus far, there have been no nationwide large-scale surveys regarding the status of iodine intake among postpartum women in Korea. Therefore, we conducted a nationwide survey of postpartum dietary iodine intake among Korean women. In total, 1054 Korean women aged ≥19 years, at less than 8 weeks postpartum, participated in this survey. Dietary data were collected using self-reported 2-day dietary records, along with before-and-after meal photos. To evaluate the correlation between dietary iodine and urinary iodine excretion (UIE), spot urine, and 24 h urine samples were collected from 98 and 29 participants, respectively. The mean daily iodine intake among all participants was 2945.6 μg, and it gradually decreased over time after childbirth. Dietary iodine intake was significantly correlated with 24 h UIE (r = 0.396, p < 0.05) and spot urine UIE (r = 0.312, p < 0.05). Follow-up studies are required to examine the influence of excessive postpartum iodine intake on thyroid health in mothers and their infants.