Value of the Indicators of Urinary Iodine Metabolism in Identifying Iodine Excess during Pregnancy

Objective To assess the application value of indicators of iodine metabolism in identifying iodine excess during pregnancy. Methods The clinical data were collected and analyzed of pregnant women undergoing hysterosalpinography (HSG) examination before pregnancy and pregnancy nutrition consultation or management in the Clinical Nutrition Department of Peking Union Medical College Hospital from January to December 2018. Serum iodine> 90 μg/L is used as the gold standard for diagnosing iodine overdose, and the difference of random urine iodine, urine iodine-to-creatinine ratio, and 24-hour urine iodine excretion rate, were compare between pregnant women with serum iodine> 90 μg/L and pregnant women ≤ 90 μg/L. Spearman correlation method was used to analyze the correlation between the above indicators of iodine metabolism and serum iodine. The receiver operating characteristic curve (ROC) was used to analyze the clinical value of random urine iodine, urine iodine-to-creatinine ratio, and 24-hour urine iodine excretion rate in the diagnosis of iodine excess. Results 70 pregnant women meeting the inclusive and exclusive criteria were included in the study. The median value of serum iodine was 138.00 (79.00, 510.50) μg/L, 50 cases (71.43%) of serum iodine> 90 μg/L, 20 cases (28.57%) ≤ 90 μg/L. The random urine iodine, urine iodine-to-creatinine ratio, and 24-hour urine iodine excretion rate of pregnant women with serum iodine >90 μg/L were significantly higher than those pregnant women with serum iodine ≤ 90 μg/L (all P 0.05). Conclusions Women with a history of iodine exposure before pregnancy have a higher rate of excess iodine during pregnancy. Random urine iodine, urine iodine-to-creatinine ratio, and 24-hour urine iodine excretion rate have certain application value in identifying iodine excess during pregnancy in women with a history of iodine exposure before pregnancy. Because urine iodine-creatinine ratio is convenient to detect, that of >307.5μg/g Cr may help to further improve the recognition rate of excess iodine during pregnancy.