Abstract
PurposePregnant women in Sweden are mildly iodine deficient. We investigated the effect of daily iodine supplementation on the iodine and thyroid status of pregnant women.MethodsIn this pilot, randomized, double-blind trial, 200 thyroid-healthy pregnant women were recruited at mean (standard deviation) pregnancy week 8.85 (1.62) and assigned (1:1) to daily intake of a multivitamin tablet with or without 150 μg of iodine. Urine and serum samples were collected at baseline and once during the second and third trimesters. Urinary iodine concentration (UIC), serum thyroglobulin (Tg), thyroid-stimulating hormone (TSH), free thyroxine (FT4), and thyroid peroxidase antibodies (TPOabs) were analyzed. Neonatal TSH data were collected. UIC and Tg were also analyzed in a group of 89 thyroid-healthy non-pregnant women of reproductive age (WRA).ResultsAt baseline, the intervention and the control groups had similar median UIC (interquartile range (IQR)): 110 μg/L (74–119) and 111 μg/L (66–168), respectively. The intervention group reached iodine sufficiency with median UIC (IQR) 139 μg/L (89–234) and 136 μg/L (91–211) in the second and third trimester, respectively, without significant difference from the lower limit of the recommended range, i.e. 150–250 μg/L (p = 0.42 and p = 0.87, respectively). The intervention group had higher median UIC and lower median Tg compared to the control group during the second (p < 0.001 and p = 0.019, respectively) and third trimester (p < 0.001 and p = 0.003, respectively), whereas thyroid hormones, serum TPOabs, and neonatal TSH were similar. The WRA group presented median UIC (IQR) 65 μg/L (30–98) and median Tg (IQR) 18 μg/L (13–27).ConclusionA daily supplement containing 150 μg of iodine to a group of pregnant women with mild iodine deficiency improved the iodine status from mild ID to iodine sufficiency. This improvement seems to have had a positive impact on maternal thyroglobulin. This study is now under extension to investigate the children’s neuropsychological development.Trial registrationClinicalTrials.gov Identifier NCT02378246, May 3, 2015, retrospectively registered.
Highlights
IntroductionModerate-to-severe iodine deficiency in adults may lead to goiter and hypothyroidism
Iodine is needed for the production of thyroid hormones
The average pregnancy week at evaluation in the third trimester was half a week later for the control group compared to the intervention group
Summary
Moderate-to-severe iodine deficiency in adults may lead to goiter and hypothyroidism. The mild form of iodine deficiency may lead to goiter with unaltered levels of thyroid hormones and elevated levels of thyroglobulin (Tg). The general population in Sweden is considered long-term iodine sufficient. This was confirmed in 2007 after our national study of school-aged children (6–12 years) showed no iodine deficiency-associated goiter [19] and a median urinary iodine concentration (UIC) of 125 μg/L [20], which is within the recommended range of 100–200 μg/L [21, 22]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
