Pan Z, et al. - Researchers assessed the association of serum iodine concentration (SIC) with urinary iodine concentration (UIC) and thyroid function in pregnant women, as well as providing a reference range of SIC for pregnant women in the area of iodine-sufficiency. From March 2016 to May 2017, they enrolled pregnant women in the Department of Obstetrics, Tanggu Maternity Hospital, Tianjin. This study included 1099 participants. Data reported that pregnant women with a SIC <79.9μg/L had a higher risk of hypothyroxinemia vs those with higher SIC. Compared to those with lower SIC values, those having SIC >138.5μg/L were more likely to have thyrotoxicosis. Findings suggested an association of serum iodine level with UIC and thyroid function in pregnant women. Investigators found that low SIC was correlated with increased risk for iodine deficiency and hypothyroxinemia. On the other hand, high SIC was related to excess and thyrotoxicosis.