Iodine deficiency in pregnant women after the adoption of the new provincial standard for salt iodization in Zhejiang Province, China

Abstract

BackgroundZhejiang has achieved the goal of elimination of iodine deficiency disorders (IDD) via the implementation of universal salt iodization (USI) since 2011. Iodine content in household table salt decreased from the national standard (35 ppm) to the Zhejiang provincial standard (25 ppm) in 2012. It is crucial to periodically monitor iodine status in pregnant women because IDD in pregnancy have adverse effects on fetal neurodevelopment.MethodsWe carried out a cross-sectional study between April 2014 and September 2015 in the eight sentinel surveillance counties across Zhejiang Province, where IDD was previously known to be endemic. A total of 1304 pregnant women participated and provided a random spot urine sample and a household table salt sample. Urinary iodine concentration (UIC) was determined using arsenic-cerium catalytic spectrophotometry. Iodine content in salt was measured using a titration method with sodium thiosulphate.ResultsOverall, the median UIC of the total study population of pregnant women was 129.3 μg/L, with a higher UIC in inland (152.54 μg/L) and a lower UIC in coastal counties (107.54 μg/L). Household coverage of iodized salt was 94.6% and the rate of adequately iodized salt was 89.9%.ConclusionsOur results indicate deficient iodine status in the pregnant population of Zhejiang, according to the lower cut-off value of optimal iodine nutrition (150 μg/L) recommended by the World Health Organization. In addition to sustaining USI, more efforts are urgently needed to improve iodine intake in women during pregnancy, especially those residing in the coastal counties.

A cross-sectional research of iodine status of pregnant women in Chongqing, south-west China

“…Especially among those using adequately iodized table salt, 40•81 % of them were still identified as iodine deficient, indicating that there was still a proportion of pregnant women with iodine insufficient status in some areas of Chongqing. Our study found no significant association between UIC of pregnant women and different iodine content in household table salt, which is different from other studies (11,12) and could be explained by the following two reasons. First, research has shown that iodized salt contributes 63•50 % of food iodine, but 24•60 % of this iodine is lost in cooking (16) .…”

“…Compared with other research in different provinces of China, the overall median UIC of pregnant women in Chongqing (171•90 μg/l) obtained in the present study is lower than that of Henan Province (204•20 μg/l in 2013 and 202•50 μg/l in 2014), but higher than in Zhejiang (130•47 μg/l) and Fujian Provinces (136•60 μg/l of Xiamen city), which did not meet the requirement level recommended by the WHO (14) . Zhejiang and Fujian had adopted the new provincial standard for iodized salt of 25 mg/kg in 2012 and then found pregnant women overall were iodine deficient in the following years (1,12) . Inadequate iodine intake in the two coastal provinces may be related to their lower provincial standard of iodized table salt.…”

“…Chongqing chose the highest level of 30 mg/kg. Previous studies showed iodine deficiency still existed among some pregnant women even with generally adequate iodine intake (10)(11)(12) . It is important to regularly monitor the iodine status in the most susceptible and vulnerable groups because even mild iodine deficiency may impair neuropsychological and motor development in children (11) .…”

Exploration of the appropriate recommended nutrient intake of iodine in healthy Chinese women: an iodine balance experiment

“…Chemical analyses of food, excreta and serum for iodine and other chemical compounds were carried out at the Central Laboratory of Preventive Medicine in Tianjin Medical University using nationally standardised and validated methods. The contents of dietary iodine and faecal iodine (25) were determined using As-Ce catalytic spectrophotometry (2,26,27) . Specimens were blindly measured in duplicate.…”

Urinary Iodine Concentration in 24-Hour Urine of Pregnant Women and Its Association with Food and Salt Intake

“…The IUC dosing method used in this study was the Sandell-Kolthoff reaction in a single sample. Thus, it is important to emphasize that this iodine deficiency in Table-4 However, even with these measures, urinary iodine was still identified below the ideal in coastal populations (107.54μg/l), through the catalytic spectrophotometry of arsenic-which suggests that measures of iodine supplementation in this population should be evaluated [21]. A study conducted in Europe with 36 pregnant women identified a high frequency of iodine deficiency (83%) even in the 150μg iodine supplementation regimen in the prenatal and postpartum periods [22].…”