Relationship Between Urinary Iodine Concentration and the Prevalence of Thyroid Nodules and Subclinical Hypothyroidism.

The aim of the study was to investigate the iodine intake in the resident population in Xi'an and analyze the relationship between iodine nutritional status and the prevalence of subclinical hypothyroidism and thyroid nodules (TNs). A total of 2507 people were enrolled in Xi'an. Venous serum thyroid stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb), urinary iodine concentration (UIC), and thyroid ultrasonography were collected. Patients with abnormal TSH were checked for free thyroxine (FT4) and triiodothyronine (FT3). Adults in Xi'an had median UICs of 220.80 µg/L and 178.56 µg/l, respectively. A sum of 16.78% of people had subclinical hypothyroidism. Both iodine excess and iodine deficit increased the frequency of subclinical hypothyroidism. The lowest was around 15.09% in females with urine iodine levels between 200 and 299 µg/l. With a rate of 10.69%, the lowest prevalence range for males was 100-199 µg/l. In Xi'an, 11.37% of people have TNs. In comparison to other UIC categories, TN occurrences were higher in females (18.5%) and males (12%) when UIC were below 100 µg/l. In conclusion, iodine intake was sufficient in the Xi'an area, while the adults' UIC remains slightly higher than the criteria. Iodine excess or deficiency can lead to an increase in the prevalence of subclinical hypothyroidism. Patients with iodine deficiency are more likely to develop TNs.

Association between Urinary Iodine Concentration and Thyroid Nodules in Adults: A Cross-Sectional Study in China.

BACKGROUND: Associations between iodine intake and thyroid nodules (TNs) were not consistent. We aimed to illustrate the relationship between urinary iodine concentration (UIC) and TNs. METHODS: A total of 12,698 participants were enrolled in analysis. All of the participants filled out questionnaires and underwent physical examinations, laboratory tests, and thyroid ultrasonography. UIC, serum thyrotropin (TSH), thyroid peroxidase antibodies (TPOAb), and thyroglobulin antibodies (TgAb) were measured in the central laboratory. RESULTS: The prevalence of TNs was 16.00%, and the median UIC was 206.1 µg/L. TNs and UIC were negatively related when UIC was less than 527 µg/L (adjusted OR = 0.87; 95% CI, 0.80, 0.94), and the relationship between UIC and TNs was not statistically significant when UIC was greater than 527 µg/L (adjusted OR = 1.25; 95% CI, 0.98, 1.60). In women, UIC was negatively associated with risk for TNs (adjusted OR 0.95; 95% CI, 0.91, 0.99). CONCLUSION: The relationship between TNs and UIC differed between men and women. The risk of TNs decreased with the elevation of UIC in men when UIC was lower than 527 µg/L, while UIC and the presence of TNs were negatively correlated in women. In the future, cohort studies or other studies that can explain causality must be conducted to explore the relationship between iodine status and TNs.

Establishing reference intervals for urine and serum iodine levels: A nationwide multicenter study of a euthyroid Chinese population.

CONTEXT: Urinary iodine (UI) is commonly used for evaluating iodine status, whereas serum iodine (SI) is more closely correlated with bioavailable iodine. However, no reliable reference intervals (RIs) for clinical use are available. We aimed to establish RIs for SI, UI, and a ratio of UI to urinary creatinine (U-Cre) applicable to the Chinese population. METHODS: This multicenter cross-sectional study enrolled 930 apparently healthy adults from six representative cities in China (Beijing, Dongying, Guiyang, Urumqi, Shenzhen, and Qiqihar) in 2017. Thyroid ultrasonography and thyroid function tests, including antithyroid antibody tests, were performed to exclude individuals with latent thyroid diseases. An iodine intake-related questionnaire survey was performed. SI and UI were measured using inductively coupled plasma-mass spectrometry. Possible influencing factors of iodine levels were evaluated using multiple regression analysis. RESULTS: Post-exclusion, the final analysis included 894 individuals. Seafood intake frequency was positively correlated with SI (standardized partial regression coefficient = 0.23) but not with UI and UI/U-Cre. SI was positively correlated with serum TT4 (Spearman correlation coefficient: 0.40), TT3 (0.23), and FT4 (0.18). SI and UI showed no age- or sex-specific variations. Significantly higher UI/U-Cre values were observed in Qiqihar than in Beijing, Guizhou, and Shenzhen. Shenzhen showed the lowest UI levels among all evaluated cities. With application of latent abnormal values exclusion procedurere, the RIs for SI, UI, and UI/U-Cre in the population were 36.0-79.3 µg/L, 19-385 µg/L, 22-450 µg/g, respectively. CONCLUSIONS: We established RIs for UI and SI among healthy Chinese individuals with no thyroid nodule or dysfunction.

Bisphenol A exposure and risk of thyroid nodules in Chinese women: A case-control study.

BACKGROUND: Thyroid nodules (TNs) are highly prevalent worldwide and have a pattern of female predominance. Bisphenol A (BPA) is an endocrine disruptor that can lead to adverse effects in human health. However, epidemiologic studies revealing the association between BPA exposure and TNs are limited and the results are inconsistent. We aimed to examine the association between urinary BPA and TNs in women who are more susceptible to TNs. METHODS: We conducted a case-control study with 1416 women aged 18 years or older (705 cases, 711 controls). All participants underwent thyroid ultrasonography. Urinary total BPA (free and conjugated) concentration was quantified using the HPLC-MS/MS. We analyzed the association between urinary BPA concentration and the risk of TNs using crude and multivariable logistic regression models. Participants were further stratified into thyroid autoantibody positive group (at least one positive) and thyroid autoantibody negative group (both negative) according to the thyroglobulin antibody (TGAb) and thyroid peroxidase antibody (TPOAb) levels, and restricted cubic spline regression was also applied to determine the possible nonlinear relationship between urinary BPA and TNs. RESULTS: Compared with women in the first quartile, the odds of TNs was 72% (adjusted OR = 1.72, 95% CI: 1.25 to 2.35) higher for those in the second quartile, 54% (adjusted OR = 1.54, 95% CI: 1.12 to 2.12) higher for those in the third quartile, and 108% (adjusted OR = 2.08, 95% CI: 1.50 to 2.90) higher for those in the fourth quartile after adjusting for age, BMI, education, HDL-C, LDL-C, triglyceride, total cholesterol, urinary iodine, TGAb and TPOAb. When the study population was stratified into thyroid autoantibody positive group and thyroid autoantibody negative group, we found that only in the positive group, the association was significant in model 1 (crude OR = 2.80; 95% CI = 1.90 to 4.12), model 2 (adjusted OR = 2.84; 95% CI = 1.91 to 4.22), model 3 (adjusted OR = 4.01; 95% CI = 2.57 to 6.27) and model 4 (adjusted OR = 3.71; 95% CI = 2.36 to 5.83). Multivariable-adjusted restricted cubic spline analysis demonstrated a similar result that in the thyroid autoantibody positive group, the association between urinary BPA and TNs risk was near linear (P-overall <0.001; P-non-linear = 0.054). CONCLUSION: In Chinese women, higher urinary BPA concentration was associated with increased risk of TNs only in those with positive thyroid autoantibodies. Moreover, this association was near linear, indicating that any rise in BPA exposure was associated with elevated TNs risk.

High Urinary Iodine, Thyroid Autoantibodies, and Thyroid-Stimulating Hormone for Papillary Thyroid Cancer Risk.

Thyroid nodules have become a common clinical problem, and the clinical importance of thyroid nodules lies in the determination of thyroid cancer. This study aims to evaluate the risk factors for papillary thyroid cancer (PTC) with regard to urinary iodine concentration (UIC), thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TGAb) in comparison to thyroid nodular goiter (NG). Among the 2041 patients, 43.8% of which showed more than adequate (UIC 200-299 µg/L) and excessive iodine (UIC ≥ 300.0 µg/L) status. Compared with adequate iodine intake, iodine deficiency (UIC < 100 µg/L) was inversely associated with multifocality (OR 0.59, P = 0.040), while more than adequate iodine intake was independently associated with an increased risk of larger tumor size (OR 1.33, P = 0.002) in female PTC patients but not in males. No significant difference in UIC was observed between patients with PTC and NG, suggesting that high iodine intake may be related with the growth of PTC, but not with its oncogenesis. Besides, positive for TPOAb and TGAb were individually associated with papillary thyroid microcarcinoma (PTMC) risk (OR 2.05 and 1.71, respectively, both P < 0.05) in female patients with tumor foci < 1 cm but not in males. Furthermore, younger age (< 46 years), TGAb positivity and small thyroid nodules in both sexes, higher TSH, TPOAb positivity, and multifocality in females could all predict PTC risk (all P < 0.05). These results might have clinical significance for managing patients with thyroid nodules and those with thyroidectomy.

Serum and urine 1H NMR-based metabolomics in the diagnosis of selected thyroid diseases.

Early detection of nodular thyroid diseases including thyroid cancer is still primarily based on invasive procedures such as fine-needle aspiration biopsy. Therefore, there is a strong need for development of new diagnostic methods that could provide clinically useful information regarding thyroid nodular lesions in a non-invasive way. In this study we investigated 1H NMR based metabolic profiles of paired urine and blood serum samples, that were obtained from healthy individuals and patients with nodular thyroid diseases. Estimation of predictive potential of metabolites was evaluated using chemometric methods and revealed that both urine and serum carry information sufficient to distinguish between patients with nodular lesions and healthy individuals. Data fusion allowed to further improve prediction quality of the models. However, stratification of tumor types and their differentiation in relation to each other was not possible.

The application of serum iodine in assessing individual iodine status.

CONTEXT: The prevalence of thyroid disease in China is on the rise, and this could be partly associated with excessive iodine intake in some individuals; therefore, increased attention is being paid to individual iodine status. However, current indices are not appropriate for evaluating individual iodine status. OBJECTIVE: To evaluate the association between serum iodine and urinary iodine (UI), as well as thyroid diseases, and provide an excellent base for future individual iodine status assessment. DESIGN, SUBJECTS AND MEASUREMENTS: A total of 902 adults were enrolled in this study including 325, 286 and 291 subjects from regions in China where iodine is adequate, sufficient and in excess, respectively. Serum iodine, UI and thyroid function were assessed, and ultrasonography performed in all subjects. RESULTS: The median serum iodine values of adults with subclinical hypothyroidism, high serum autoantibody and thyroid nodules were significantly higher than those of euthyroid adults (P<0.05). A serum iodine level higher than 100 µg/L was considered as a risk factor for thyroid diseases. Serum iodine had strong nonlinear correlations with UI and thyroid function. When thyroid function was taken as a gold standard, the area under the receiver operating characteristic (ROC) curve for serum iodine was 0.752 and UI was 0.507 for subjects with lower serum iodine and UI levels. The area for serum iodine was 0.773 and UI was 0.638 for subjects with higher serum iodine and UI levels. The areas under these curves were significantly different (P<0.001). CONCLUSION: In adults, serum iodine had a strong nonlinear correlation with UI and a high level of serum iodine was a risk factor for thyroid diseases.

Strong association of high urinary iodine with thyroid nodule and papillary thyroid cancer.

This study demonstrates a strong association of high urinary iodine with thyroid nodules and papillary thyroid cancer as well as aggressive cancer features, suggesting that high urinary iodine is a risk factor for thyroid cancer. The risk of high iodine intake for thyroid cancer has been suggested but not established. The objective of the study was to evaluate the relationship between urine iodine levels and thyroid nodule and thyroid cancer. We preoperatively tested fasting urine iodine in 154 thyroid nodule patients and correlated the results with pathological diagnoses and compared with 306 subjects as normal control. The median urine iodine (MUI) was 331.33 µg/L in patients with benign thyroid nodules versus 466.23 µg/L in patients with papillary thyroid cancer (PTC) (P=0.003), both of which were in the excessive iodine state and higher than the MUI of 174.30 µg/L in the control group (P < 0.001), which was in the sufficient iodine state. Excessive iodine state (MUI>300 µg/L) was seen in 62.75% of patients with benign thyroid nodules and 66.99% of patients with PTC, both of which were significantly higher than the iodine excessive rate of 19.93% in the control group (P<0.001). Moreover, MUI in patients with PTC with lymph node metastasis was significantly higher than that of PTC patients without lymph node metastasis (P<0.001). Urine iodine of thyroid cancer patients with stage III and IV disease was significantly higher than that of patients with stage I and II diseases (P<0.001). Multivariable analyses showed that, like sand calcification of thyroid nodule and TSH, urine iodine was an independent risk factor for PTC. These data demonstrate a significant association between high urinary iodine and benign and malignant thyroid nodules and PTC aggressiveness, supporting high urinary iodine as a risk factor for thyroid malignancy. Further studies are warranted to confirm these findings.

Sonographic and functional characteristics of thyroid nodules in a population of adult people in Isfahan.

INTRODUCTION: The aim of this study was to investigate the current status of sonographic characteristics of thyroid nodules in Isfahan, a previously iodine deficient area in central Iran. MATERIAL AND METHODS: In a cross-sectional study conducted in 2006, 2523 adult people (age > 20 years) were selected by a multistage clustering sampling method. Of these people, 263 volunteered persons were underwent sonographic evaluation. Thyroid examination was done by two expert sonographers. Serum T(3), T(3), T3RU, TSH, TPO Ab and Tg Ab, and urinary iodine were measured. RESULTS: Forty-six per cent of the 263 people were women. Their mean age was 35.5 years with a range of 20-64 years. Median urinary iodine was 19.4 microg/dL. The prevalence of thyroid nodules on sonography was 22.4% in the whole group; 30% in women and 16.3% in men (OR = 2.2, P = 0.01). The prevalence of thyroid nodules increased with age (P = 0.006). The prevalence of thyroid nodules was higher in hypothyroid people than in euthyroid people (35.1% v. 20.5%, OR = 2.1, P = 0.04). Neither urinary iodine nor autoantibody concentrations correlated with the prevalence of thyroid nodules in sonography. CONCLUSIONS: The prevalence of thyroid nodule by sonography is still high despite relatively normal urinary iodine in this population.

[Volume and echostructure of the thyroid and ioduria in an urban population of adults in the southeastern Polish city of Rzeszów]. / Objetosc i echostruktura tarczycy oraz joduria w miejskiej populacji osób doroslych w Rzeszowie.

The aim of this work was to determine the volume and echostructure of the thyroid and to examine urinary iodine excretion in an adult population of residents of Rzeszów, a city located in the Carpathian endemic region for goiter, after the introduction of mandatory iodine prophylaxis in 1997. 984 subjects, aged 19-60, were examined (540 females and 394 males). The mean level of urinary iodine in the examined population was 104.17 microg/l (+/- 85.22). Higher urinary iodine levels were seen in the group of males (p = 0.005) and in those who were taking medication containing iodine (p = 0.002). The mean volume of the thyroid in the examined group was 18.69 (+/- 10.01) ml and was larger in the group of males than females (p < 0.005). Nodular lesions were found in 17% of the examined thyroids and a statistically significant prevalence in the group of females (20.8%) over the group of males (11.4%) was found (p < 0.0005). The occurrence of nodules increased with age and was significantly higher in the 40-60 year age group than in the 19-25 years age group (p = 0.001). In single--and multi--factor analysis, a correlation was found between the occurrence of nodules and the female gender (r-2.04, 3.48; p < 0.005, < 0.0005) and the occurrence of nodules and the volume of the thyroid (r-1.1, 1.11; p < 0.005, < 0.0005). The occurrence of nodules did not correlate with ioduria (r-1, p = 0.8). Iodine prophylaxis was shown to be highly effective, although the examined region does not yet meet the criteria for the elimination of iodine deficiency as formulated by the ICCIDD.

Goitre prevalence and thyroid abnormalities at ultrasonography: a comparative epidemiological study in two regions with slightly different iodine status.

OBJECTIVE: The association between severe iodine deficiency and endemic goitre is well established, but little information is available on the relation between milder degrees of iodine deficiency and goitre prevalence. SUBJECTS: In a comparative epidemiological study performed in two regions in Denmark, we examined 4649 subjects from the general population, women aged 18-65 years and men aged 60-65 years. METHODS: Ultrasonography and palpation of the thyroid was performed in all participants. Iodine excretion was measured in casual urine samples. Previous thyroid disease was detected by questionnaires, personal interviews and tracing of records. RESULTS: The median iodine excretion was 61 microg/l (mild iodine deficiency (ID)) and 45 microg/l (moderate ID) in the two regions. Median thyroid volume at ultrasonography was 11. 9 ml (mild ID) and 13.6 ml (moderate ID), P <0.001, and thyroid enlargement was found in 15.0% (mild ID) and 22.6% (moderate ID), P<0.001. Goitre prevalence increased in both regions with age to the age group 40-45 years, but not after that age. Subjects who had moved from the moderate ID to the mild ID area had the same prevalence of thyroid enlargement as the subjects staying permanently in the mild ID area. Thyroid nodules at ultrasonography were found in 30% in both regions, but nodules were larger and more often palpable in the moderate ID area. Palpable goitre was found in 9.8% (mild ID) and 14.6% (moderate ID), P<0.001. The greatest regional difference in thyroid abnormalities was found among men. CONCLUSION: Marked differences in the prevalence of thyroid abnormalities were found in these regions with modest differences in iodine excretion.