Association between excessive chronic iodine exposure and the occurrence of papillary thyroid carcinoma

The correlation between urinary iodine levels and gallstone risk: elevated iodine intake linked to gallstone occurrence

Background

Essential trace elements are vital for human growth and development. Nevertheless, excessive intake can pose risks. As of yet, no research has looked at the possibility of a relationship between the prevalence of gallstones and urinary concentrations of nickel, molybdenum, and iodine.

Objectives

The purpose of this study was to examine the correlation between urinary levels of iodine, molybdenum, and nickel and the occurrence of gallstones in a U.S. population and to verify whether excessive iodine intake is associated with the occurrence of gallstones.

Methods

Data from 2,734 participants that were gathered between 2017 and 2020 were examined. Employing inductively coupled plasma mass spectrometry (ICP-MS), the levels of nickel (Ni), iodine (I), and molybdenum (Mo) in the urine were determined. Gallstones presence was determined using a standardized questionnaire. Restricted cubic spline analysis, subgroup analysis, and logistic regression analysis were used to evaluate the relationship between the occurrence of gallstones and urinary essential trace elements.

Results

The logistic regression analysis indicated an increased risk of gallstone development in Quartiles 2, Quartiles 3, and Quartiles 4 groups in comparison to the Quartiles 1 group, based on urinary iodine levels (OR = 1.69, 95% CI: 1.11-2.56; OR = 1.68, 95% CI: 1.10-2.55; OR = 1.65, 95% CI: 1.09-2.51). Urinary iodine levels were nonlinearly positively linked with the development of gallstones, according to restricted cubic spline analysis (P-Nonlinear = 0.032). Subgroup analyses showed that high levels of urinary iodine were associated with a high risk of gallstones in different populations, and were more pronounced in adults aged 60 years and older, in women, with a BMI ≥ 25, and in diabetic patients.

Conclusion

Our research revealed a correlation between an increased risk of gallstones and increasing urinary iodine levels. Urinary iodine levels serve as indicators of the body's iodine status, thus suggesting that excessive iodine intake may be linked to an elevated risk of gallstone formation.

Circ_0004851 regulates the molecular mechanism of miR-296-3p/FGF11 in the influence of high iodine on PTC

The prevalence of papillary thyroid cancer (PTC) has been rising in recent years. Despite its relatively low mortality, PTC frequently metastasizes to lymph nodes and often recurs, posing significant health and economic burdens. The role of iodine in the pathogenesis and advancement of thyroid cancer remains poorly understood. Circular RNAs (circRNAs) are recognized to function as competing endogenous RNAs (ceRNAs) that modulate gene expression and play a role in various cancer stages. Consequently, this research aimed to elucidate the mechanism by which circRNA influences the impact of iodine on PTC. Our research indicates that high iodine levels can exacerbate the malignancy of PTC via the circ_0004851/miR-296-3p/FGF11 axis. These insights into iodine's biological role in PTC and the association of circRNA with the disease could pave the way for novel biomarkers and potentially effective therapeutic strategies to mitigate PTC progression.

Association between iodine nutrition and cervical lymph node metastasis of papillary thyroid microcarcinoma

We aimed to investigate the association between iodine intake and nodal metastasis stratified by central lymph node metastasis (CLNM) and lateral lymph node metastasis (LLNM) of papillary thyroid microcarcinoma (PTMC). Urinary iodine concentration (UIC) and clinicopathological characteristics were used to identify factors associated with CLNM and LLNM using logistic regression analysis. A sum of 3,858 PTMC patients were enrolled. The median UIC (MUI) of patients with CLNM or LLNM was not statistically different from those without nodal metastasis. Male patients had a higher MUI than females (183.4 μg/L vs. 173.6 μg/L). Female patients with extracapsular extension had a higher MUI than those without it (210.0 μg/L vs. 172.1 μg/L). Male patients with LLNM had a significantly lower MUI than those without LLNM (134.7 μg/L vs. 187.9 μg/L). Female patients with more than adequate iodine intake were more likely to present with CLNM and extrathyroidal extension than those with adequate iodine intake with an odds ratio (95% confidence interval) of 1.23 (1.01-1.51) and 1.59 (1.09-2.32) after adjustment. Iodine nutrition was not found to be associated with LLNM. In addition, patients with a younger age, larger tumors, extrathyroidal extension, and intrathyroidal spread were more likely to be CLNM, whereas nodular goiter presented with a protective factor; CLNM was the only factor associated with LLNM of PTMC in both genders. In conclusion, iodine nutrition has a much closer association with female than male patients, and high iodine intake may be associated with CLNM and extrathyroidal extension in female PTMC patients.

The relationship between urinary iodine concentration and papillary thyroid cancer: A systematic review and meta-analysis

BACKGROUND

The effect of iodine on papillary thyroid cancer (PTC) has been controversial for many years. Since urinary iodine is an effective indicator of iodine intake, some recent epidemiological studies have described the relationship between urinary iodine concentration (UIC) and PTC.

METHODS

We searched PubMed, Embase, Cochrane Library, and Web of Science for case-control studies about UIC and PTC published before September 2022. Results are presented as the overall odds ratio (OR) and 95% confidence intervals (CI).

RESULTS

According to the analysis of the included studies, excessive iodine intake (UIC≥300ug/L) was positively associated with the occurrence of PTC patients compared with healthy controls (OR4.05, 95%CI 1.64-10.02, P=0.002). Meanwhile, adequate iodine exposure (100≤UIC<200ug/L) may play a protective role in the occurrence of PTC compared with healthy individuals (OR 0.36, 95%CI 0.14-0.91, P=0.03) while the difference in the prevalence of insufficient iodine intake (UIC<100ug/L) and iodine above requirements (200≤UIC<300ug/L) among the two groups were not significant (deficiency: OR 0.38, 95%CI 0.13-1.16, P=0.09; above requirements: OR 0.92, 95%CI 0.40-2.10, P=0.84). After comparing the UIC levels of PTC patients with those of other thyroid diseases, we found that there was also no significant difference in the incidence of different levels of UIC in the two groups (excessive: OR 1.25, 95%CI 0.87-1.80, P=0.22; above requirements: OR 0.93, 95%CI 0.77-1.14, P=0.49; adequate: OR 0.96, 95%CI 0.78-1.17, P=0.67; deficiency: OR 1.02, 95%CI 0.86-1.22, P=0.80). The result of this meta-analysis also did not support the relationship between UIC and the BRAF mutation and lymph node metastasis (LNM) of PTC patients. Besides, we also found that studies on the relationship between urinary iodine and PTC may be influenced by the way UIC was measured.

CONCLUSION

The 10 case-control included studies involved a total of 6,544 participants. The results of this meta-analysis showed excessive iodine intake, that is, UIC≥300ug/L was associated with the occurrence of PTC but not with BRAF mutation and LNM while adequate iodine intake (100≤UIC<200ug/L) may be one of the protective factors for PTC.

SLC34A2 Up-regulation And SLC4A4 Down-regulation Correlates With Invasion, Metastasis, And The MAPK Signaling Pathway In Papillary Thyroid Carcinomas

Papillary thyroid carcinoma (PTC) is one of the fastest growing endocrine system malignant carcinomas detected over the past decade. Unfortunately, more than 25% of PTC patients are characterized by their aggressiveness and subsequent metastasis; these characteristics usually indicate poor prognosis. Recently, increasing evidence has suggested that solute carrier (SLC) transporters may play a pivotal role in the initiation, invasion and metastasis of human carcinoma. However, the expression and clinicopathological significance of SLC transporters in patients with PTC remains undetermined. In this study, we aimed to elucidate how the differential expression of SLC transporters affects clinicopathological features, as well as determine the possible regulatory signaling pathways involved. Three differentially expressed SLC transporters were screened from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) database using a bioinformatics approach. The results indicated that high SLC34A2 and low SLC4A4 protein expression exhibited a higher percentage of capsular invasion and extra-thyroid metastasis in patients. Logistic regression analysis showed that high SLC34A2 expression in tumors was identified as an independent risk factor for capsular invasion [odds ratio (OR)=11.400, 95% confidence interval (CI)=1.733-74.995, P=0.011] and extra-thyroid metastasis (OR=4.920, 95%CI=1.234-19.623, P=0.024), while low SLC4A4 expression in tumors was only identified as independent risk factors for extra-thyroid metastasis (OR=8.568, 95%CI =1.186-61.906, P=0.033). Specifically, for tumors with capsular invasion and extra-thyroid metastasis, the protein expression staining of SLC34A2 was markedly enhanced in the cytoplasm of follicular epithelial cells, contrastingly, SLC4A4 expression was notably weakened in the cytomembrane and nucleus. Intriguingly, both high SLC34A2 and low SLC4A4 protein expression were significantly linked to a high urinary iodine concentration in patients with PTC. Mechanistically, compared with adjacent normal thyroids, p-ERK was significantly up-regulated by 17.8% in the invading tumor; p-ERK, p-JNK, and p-P38 were markedly up-regulated by 29.2%, 67.1%, and 38.9% for metastatic tumors, respectively. Importantly, SLC4A4 negatively correlated with p-JNK (r=-0.696, P= 0.004) and p-P38 (r=-0.534, P=0.049). In conclusion, we suggest that up-regulated SLC34A2 (mainly in the cytoplasm) and down-regulated SLC4A4 (mainly in the cytomembrane and nucleus), which might be attributed to excess iodine intake, were closely linked to extra-thyroid metastasis in PTCs. Furthermore, this effect of SLC4A4 may be through the activation of JNK/P38 MAPK signaling pathway. Future in vivo and in vitro gain- or loss-of-function experiments are needed to verify these findings and further elucidate the deeper molecular mechanisms.

Association between Iodine Intake, Thyroid Function, and Papillary Thyroid Cancer: A Case-Control Study

BACKGROUND

This study aimed to assess the effects of iodine intake, thyroid function, and their combined effect on the risk of papillary thyroid cancer (PTC) and papillary thyroid microcarcinoma (PTMC).

METHODS

A case-control study was conducted including 500 community-based controls who had undergone a health check-up, and 446 overall PTC cases (209 PTC and 237 PTMC) from the Thyroid Cancer Longitudinal Study. Urinary iodine concentration (UIC), was used as an indicator of iodine intake, and serum for thyroid function. The risk of PTC and PTMC was estimated using unconditional logistic regression.

RESULTS

Excessive iodine intake (UIC ≥220 μg/gCr) was associated with both PTC (odds ratio [OR], 18.13 95% confidence interval [CI], 8.87 to 37.04) and PTMC (OR, 8.02; 95% CI, 4.64 to 13.87), compared to adequate iodine intake (UIC, 85 to 219 μg/gCr). Free thyroxine (T4) levels ≥1.25 ng/dL were associated with PTC (OR, 1.97; 95% CI, 1.36 to 2.87) and PTMC (OR, 2.98; 95% CI, 2.01 to 4.41), compared to free T4 levels of 0.7 to 1.24 ng/dL. Individuals with excessive iodine intake and high free T4 levels had a greatly increased OR of PTC (OR, 43.48; 95% CI, 12.63 to 149.62), and PTMC (OR, 26.96; 95% CI, 10.26 to 70.89), compared to individuals with adequate iodine intake and low free T4 levels.

CONCLUSION

Excessive iodine intake using creatinine-adjusted UIC and high free T4 levels may have a synergistic effect on PTC and PTMC. Considering both iodine intake and thyroid function is important to assess PTC and PTMC risk.

Evaluation of Iodine Status among Korean Patients with Papillary Thyroid Cancer Using Dietary and Urinary Iodine

BACKGROUND

Concerns have been raised regarding thyroid disorders caused by excessive iodine in Koreans, who have iodine-rich diets. This study evaluated iodine status using dietary iodine intake and urinary iodine in papillary thyroid cancer (PTC) patients.

METHODS

Dietary data of PTC patients were assessed using a 24-hour recall and food frequency questionnaire (FFQ), and urinary iodine concentrations (UICs) were also obtained. To compare the iodine status of PTC patients, Korean adults with or without thyroid disease from the Korea National Health and Nutrition Examination Survey, which had 24-hour recall data and urinary iodine measurements, were analyzed.

RESULTS

The median daily iodine intake by 24-hour recall was 341.7 μg/day in PTC patients, similar to the levels of other Korean adults. Based on UICs, the prevalence of excessive iodine was 54.4% in PTC patients, which was similar to the prevalence among subjects with thyroid disease (55.4%) but slightly higher than that in subjects without thyroid disease (47.7%). Based on dietary iodine by 24-hour recall, the prevalence of excessive iodine intake was 7.2%, which was higher than that among subjects with (4.4%) or without (3.9%) thyroid disease. The dietary iodine intake based on 24-hour recall was closely correlated with the UIC (r=0.4826) in PTC patients, but dietary iodine by FFQ was not significantly correlated with either 24-hour recall or UIC-based dietary iodine.

CONCLUSION

Excessive iodine intake was more common in PTC patients than in subjects without thyroid disease. Further longitudinal research is necessary to elucidate the role of dietary iodine in PTC.