{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T14:00:13Z","timestamp":1789999213504,"version":"4.0.1"},"reference-count":46,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,20]],"date-time":"2026-09-20T00:00:00Z","timestamp":1789862400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Tianjin Health Research Project","award":["TJWJ2024QN091"],"award-info":[{"award-number":["TJWJ2024QN091"]}]},{"award":["TJWJ2024QN091"],"award-info":[{"award-number":["TJWJ2024QN091"]}],"id":[{"id":"https:\/\/ror.org\/059qgvg50","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["82173641"],"award-info":[{"award-number":["82173641"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"award":["82173641"],"award-info":[{"award-number":["82173641"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Tianjin Key Medical Discipline Construction","award":["TJYXZDXK-3-020B"],"award-info":[{"award-number":["TJYXZDXK-3-020B"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Background\/Objectives: As dietary and environmental exposures change, interacting with genetic susceptibility, the prevalence of thyroid function abnormality and subclinical thyroid dysfunction in children is rising, yet systematic research in this population remains scarce. Methods: From 13 districts of Tianjin, China, all characterized by adequate iodine levels, 997 children between the ages of 8\u201310 years were recruited using a school-based sampling approach. Peripheral venous blood samples were drawn for genotyping analysis of two single nucleotide polymorphisms (SNPs): thyroid stimulating hormone receptor (TSHR) rs2268458 and NK2 homeobox 1 (NKX2-1) rs2076735 using the Sequenom MassARRAY platform. In addition, data on 31 non-genetic factors, including urinary iodine concentration (UIC), were collected. Restricted cubic spline (RCS) models were used to examine the non-linear associations between UIC and thyroid abnormalities. Multivariable Poisson regression was applied to identify factors associated with thyroid outcomes. Results: The overall prevalence of thyroid function abnormality in the study population was 17.35%, with detection rates of 3.51% for subclinical hyperthyroidism and 2.21% for subclinical hypothyroidism. After adjusting for age, sex, body mass index z-score (BMI-z-score), district of residence, and recruitment year, RCS models revealed significant U-shaped non-linear associations between UIC and both free triiodothyronine (FT3) abnormality (Poverall = 0.003, Pnonlinear &lt; 0.001) and overall thyroid function abnormality (Poverall = 0.042, Pnonlinear = 0.029). In multivariable analysis, after Bonferroni correction within prespecified hypothesis families, family history of thyroid disease in first-degree relatives remained significantly associated with subclinical hyperthyroidism (adjusted p = 0.015), and UIC &lt; 100 \u03bcg\/L remained significantly associated with overall thyroid function abnormality (adjusted p = 0.036). In addition, district of residence was associated with subclinical hypothyroidism after correction (adjusted p = 0.009). Stratified analyses revealed potential subgroup-specific effects. Children with the NKX2-1 rs2076735 TT + TC genotype and UIC &lt; 100 \u03bcg\/L had a higher prevalence of thyroid function abnormality compared with the reference group (UIC 100\u2013299 \u03bcg\/L) (p = 0.031, PR = 3.093, 95% CI: 1.108, 8.636). Frequent consumption of kelp or laver soup was associated with a higher prevalence of subclinical hyperthyroidism among children with the NKX2-1 rs2076735 CC genotype or the TSHR rs2268458 TT genotype (p = 0.049, PR = 3.636, 95% CI: 1.006, 13.140; p = 0.023, PR = 4.814, 95% CI: 1.245, 18.610, respectively). Among children with the NKX2-1 rs2076735 CC genotype, those with a family history of thyroid disease had a higher prevalence of subclinical hyperthyroidism (p = 0.029, PR = 4.114, 95% CI: 1.152, 14.688). After Benjamini\u2013Hochberg false discovery rate correction, none of the subgroup-specific associations remained statistically significant (adjusted p-values: 0.058\u20130.065). Conclusions: The prevalence of thyroid function abnormality and subclinical thyroid dysfunction was relatively high among school-aged children in this study population from Tianjin, China. After adjustment for covariates and correction for multiple comparisons, family history of thyroid disease, UIC &lt; 100 \u03bcg\/L, and district of residence remained significantly associated with subclinical hyperthyroidism, overall thyroid function abnormality, and subclinical hypothyroidism, respectively. A U-shaped association was observed between UIC and thyroid health, highlighting the importance of maintaining adequate iodine nutrition. However, stratified analyses suggested potential subgroup-specific associations that require validation in larger, independent cohorts.<\/jats:p>","DOI":"10.3390\/nu18183085","type":"journal-article","created":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T12:50:03Z","timestamp":1789995003000},"page":"3085","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Iodine Nutrition, Non-Genetic Factors, and Two Candidate Polymorphisms Associated with Thyroid Function Abnormalities Among Children Aged 8\u201310 Years in Iodine-Adequate Areas of Tianjin, China"],"prefix":"10.3390","volume":"18","author":[{"given":"Yani","family":"Duan","sequence":"first","affiliation":[{"name":"Institute of Environment and Public Health, Tianjin Centers for Disease Control and Prevention, 6 Huayue Road, Hedong District, Tianjin 300011, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"software","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"}]},{"given":"Yang","family":"Wang","sequence":"additional","affiliation":[{"name":"Institute of Environment and Public Health, Tianjin Centers for Disease Control and Prevention, 6 Huayue Road, Hedong District, Tianjin 300011, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Fang","family":"Li","sequence":"additional","affiliation":[{"name":"Institute of Environment and Public Health, Tianjin Centers for Disease Control and Prevention, 6 Huayue Road, Hedong District, Tianjin 300011, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Wenfeng","family":"Li","sequence":"additional","affiliation":[{"name":"Institute of Environment and Public Health, Tianjin Centers for Disease Control and Prevention, 6 Huayue Road, Hedong District, Tianjin 300011, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"supervision","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Dandan","family":"Zhang","sequence":"additional","affiliation":[{"name":"Institute of Environment and Public Health, Tianjin Centers for Disease Control and Prevention, 6 Huayue Road, Hedong District, Tianjin 300011, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"validation","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"}]},{"given":"Yushan","family":"Cui","sequence":"additional","affiliation":[{"name":"Institute of Environment and Public Health, Tianjin Centers for Disease Control and Prevention, 6 Huayue Road, Hedong District, Tianjin 300011, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"conceptualization","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Cammisa, I., Rigante, D., and Cipolla, C. 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