Abstract
Background: Iodine supplementation during pregnancy in areas with mild-to-moderate iodine deficiency is still debated. Methods: A single-center, randomized, single-blind and placebo-controlled (3:2) trial was conducted. We enrolled 90 women before 12 weeks of gestation. From enrollment up until 8 weeks after delivery, 52 women were given an iodine supplement (225 ug/day, potassium iodide tablets) and 38 were given placebo. At recruitment (T0), in the second (T1) and third trimesters (T2), and 8 weeks after delivery (T3), we measured participants’ urinary iodine-to-creatinine ratio (UI/Creat), thyroid function parameters (thyroglobulin (Tg), TSH, FT3, and FT4), and thyroid volume (TV). The newborns’ urinary iodine concentrations were evaluated in 16 cases. Results: Median UI/Creat at recruitment was 53.3 ug/g. UI/Creat was significantly higher in supplemented women at T1 and T2. Tg levels were lower at T1 and T2 in women with UI/Creat ≥ 150 ug/g, and in the Iodine group at T2 (p = 0.02). There was a negative correlation between Tg and UI/Creat throughout the study (p = 0.03, r = −0.1268). A lower TSH level was found in the Iodine group at T3 (p = 0.001). TV increased by +Δ7.43% in the Iodine group, and by +Δ11.17% in the Placebo group. No differences were found between the newborns’ TSH levels on screening the two groups. Conclusion: Tg proved a good parameter for measuring iodine intake in our placebo-controlled series. Iodine supplementation did not prove harmful to pregnancy in areas of mild-to-moderate iodine deficiency, with no appreciable harmful effect on thyroid function.
Highlights
According to the World Health Organization (WHO) guidelines, median urinary iodine values≥150 ug/L are consistent with an adequate iodine intake for pregnant women [1]
Our study was conducted in an area of mild-to-moderate iodine deficiency with a sustained iodine prophylaxis program based on iodized salt, aiming to assess: (a) changes in UI/Creat induced by iodine supplementation during pregnancy and breastfeeding; (b) the relationship between iodine supplementation and thyroid function; (c) and differences in Tg levels and thyroid volume (TV)
Dropout occurred at T2 and T3: many foreign women went back to their country of origin to deliver or after delivery; other women had problems coming to our center in the late phases of pregnancy and after delivery; many others stopped taking the tablets or started taking multivitamins and were excluded from the study
Summary
According to the World Health Organization (WHO) guidelines, median urinary iodine values≥150 ug/L are consistent with an adequate iodine intake for pregnant women [1]. The effect of mild-to-moderate iodine deficiency in pregnancy (urinary iodine concentrations (UIC) between 50 and 150 ug/L) [3]. A recent survey on 6180 mother-child pairs conducted in areas of mild-to-moderate iodine deficiency found a positive, curvilinear correlation between women’s iodine/creatinine ratios (UI/Creat) before 14 weeks of gestation and their offspring’s mean verbal IQs [8]. A recent work documented how UI/Creat better reflects 24-h urinary iodine excretion and circulating iodine levels in pregnancy than UIC [12]. At recruitment (T0), in the second (T1) and third trimesters (T2), and 8 weeks after delivery (T3), we measured participants’ urinary iodine-to-creatinine ratio (UI/Creat), thyroid function parameters (thyroglobulin (Tg), TSH, FT3, and FT4), and thyroid volume (TV). Tg levels were lower at T1 and T2 in women with
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