Background: Although the policy of universal salt iodization and daily iodine-containing vitamin supplementations were implemented, the urinary iodine concentration (UIC) in pregnant women in the northeast of Thailand still showed mild iodine deficiency.

Objective: To determine UIC in pregnant women receiving daily iodine-containing vitamin versus a single dose of two iodized oil capsules.

Materials and Methods: The present study was conducted between March 2014 and October 2015, in 21 public hospitals in Khon Kaen Province. Healthy singleton pregnancy of a gestational age of less than 20 weeks that had not received iodine-containing vitamin were enrolled. The participants were asked to take either daily one tablet vitamin or a single dose of two iodized oil capsules. Random urine was collected before and after taking medication. Neonatal thyroid stimulating hormone (TSH) was retrieved from medical record.

Results: Of the 2,079 participants, median UIC of pre- and post-daily vitamin supplementation in 1,061 pregnant women were 116.0 and 126.2 mcg/L. Median UIC of pre- and post-single dose iodized oil in 973 participants were 110.4 and 108.6 mcg/L. There was no statistically significant increase UIC post iodine supplementation in both groups (p=0.169). The median neonatal serum TSH were 4.34 and 3.79 mU/L in daily vitamin and single dose respectively, which is significantly lower in the iodized oil group (p=0.023).

Conclusion: Post iodine supplementation either by daily vitamin or single dose did not significantly increase UIC.

Keywords: Iodine supplementation, Iodized oil, Urinary iodine concentration

DOI: doi.org/10.35755/jmedassocthai.2021.02.12153

Received 19 February 2018 | Revised 25 September 2020 | Accepted 9 October 2020