Serum Iodine Concentration as a Biomarker for Individual Iodine Nutrition and Thyroid Function in Pregnant Women: A Cross-Sectional Study in Hubei Province
Mingjuan Xu, Xin Dai, Zhen Wang, Chong Guo, Biyun Zhang, Huailan GuoAbstract
Objective:
The physiological demands of pregnancy substantially alter iodine metabolism and thyroid function. This critical period heightens the requirement for iodine, making deficiency a significant risk factor for both maternal and fetal thyroid dysfunction. This study aimed to evaluate the iodine nutritional status of pregnant women in Hubei Province, explore the relationship between serum iodine concentration (SIC) and thyroid function, and determine the prevalence of thyroid disorders.
Design:
The eligible participants underwent a face-to-face interview and completed questionnaire surveys to collect baseline information and dietary intake data. Serum thyroid hormones, thyroid antibodies, SIC, and urine iodine concentration (UIC) were measured. The 95% reference intervals of SIC were established and ROC analysis was applied to compare the predictive ability of SIC and UIC for thyroid dysfunction.
Setting:
Hubei Province, China.
Participants:
1197 eligible pregnant women were included in this study.
Results:
This study revealed a thyroid dysfunction prevalence of 28.40%, with hypothyroxinemia being the most prevalent thyroid function abnormality, accounting for 79.7% of all thyroid dysfunction cases. Significant differences in hypothyroxinemia prevalence were noted across pregnancy trimesters ( P < 0.001), with the highest prevalence in the first trimester and the lowest in the third. In the first trimester, SIC was negatively correlated with TSH ( r = –0.195, P < 0.001) and positively correlated with FT3 ( r = 0.294, P < 0.001). Additionally, SIC demonstrated a positive correlation with FT4 in each trimester (all P < 0.001). Finally, the SIC reference intervals for pregnant women in the first, second, and third trimesters were 50.08∼118.61 µg/L, 59.16∼127.44 µg/L, and 53.61∼118.67 µg/L, respectively.
Conclusions:
SIC can serve as a reliable indicator for evaluating individual iodine nutritional status and predicting thyroid dysfunction.