Poster Topical Area: Vitamins and Minerals

Location: Hall D

Poster Board Number: 500

P26-039 - Excessive exposure to iodine in pregnancy merits attention: a pilot follow-up study

Sunday, Jun 10
8:00 AM – 6:00 PM

Objective: as increasing cases of iodine excess during pregnancy have been identified, it is essential to investigate the main cause and explore its effect on maternal and fetal health.

Method: 390 pregnant women underwent iodine evaluation in antenatal care between Jan 2016 and Dec 2016. Herein, elevated urinary iodine concentration (UIC) was identified in 18 cases who were enrolled in this prospective observation study. Serum iodine concentration (SIC) was also monitored in pregnancy, with colostrum iodine concentration and neonatal UIC measured after delivery. Data of dietary iodine intake and thyroid function were also collected.

excessive dietary iodine intake was recognized in 5 women (27.8%), while exposure to oil-soluble iodinated contrast medium through pre-gestational hysterosalpingography (HSG) was confirmed in 14 women (77.8%). Based on presence of HSG history, participants were categorized into group with HSG history (HH group) and group without HSG history (non-HH group). The mean UIC (3831.2 μg/L) and SIC (849.3 μg/L) of HH group were relatively higher than that of non-HH group (UIC 458.8 μg/L; SIC 98.5 μg/L) (p=0.089 for UICs; p=0.058 for SICs). Seven subjects of HH group (including 3 with pre-existing hypothyroidism) developed overt or subclinical hypothyroidism during pregnancy, whill all subjects of non-HH group were euthyroid. Following dietary iodine restriction, the mean UIC of HH group could be significantly lowered to 744.5 μg/L (p=0.001).

Except for one spontaneous abortion case from HH group, the other 17 women had babies at full term. Significantly higher iodine concentration in colostrum was identified in HH group (710.0 μg/L) as compared to non-HH group (248.0 μg/L) (p=0.005). Neonatal UIC of infants born to mothers from HH-group (794.4 μg/L) was seemingly higher than that of non-HH group (282.0 μg/L) (p=0.082). All neonates were demonstrated negative during congenital hypothyroidism screening.

exposure to lipiodol through pre-conceptional HSG could be the most common cause of iodine excess during pregnancy, which may increase risk of thyroid dysfunction. Appropriate dietary iodine restriction and regular monitoring is indicated, and breast milk iodine content merits attention for infants receiving breastfeeding.

Funding Source: Not applicable.

CoAuthors: Yanping Liu – Peking Union Medical College Hospital; Liangkun Ma – Peking Union Medical College Hospital; Ling Qiu – Peking Union Medical College Hospital; Jianhua Han – Peking Union Medical College Hospital; Rui Li – Peking Union Medical College Hospital

Rongrong Li

Peking Union Medical College Hospital
Beijing, Beijing, China (People's Republic)