Iodine status five years after the adjustment of universal salt iodization: a cross-sectional study in Fujian Province, China

Abstract

Background Universal salt iodization program was introduced to China to eliminate iodine deficiency disorders in 1995. In 2012, Fujian Province decreased the concentration of iodized table salt according to the national unified requirement. This study aimed to assess the effect on iodine status after the adjustment, providing evidence for further adjustment in Fujian Province. Methods Sampling units were selected by multistage cluster sampling method. In each sampling unit, table salt was collected from 30 households. A total of 2,471 people in 2009 and 4,806 people in 2017 provided urine samples and were included in this cross-sectional analysis. Median iodized salt concentration and median urine iodine concentration were present by median and interquartile range. Results Median iodized salt decreased from 29.8 mg/kg in 2009 to 23.9 mg/kg in 2017. The median urinary iodine concentrations for school-age children in 2017 in coastal urban area, non-coastal urban area, coastal rural area and non-coastal rural area were 163.6µg/L (interquartile range = 100.1–252.0µg/L), 198.9µg/L (interquartile range = 128.0-294.0µg/L), 181.8µg/L (interquartile range = 114.1–257.0µg/L) and 218.2µg/L (interquartile range = 148.1-306.5µg/L), respectively. The median urinary iodine concentrations for adults in 2017 in these areas were 151.1µg/L (interquartile range = 98.3-231.7µg/L), 168.7µg/L (interquartile range = 109.6–242.0µg/L), 167.7µg/L (interquartile range = 105.7-245.7µg/L) and 182.7µg/L (interquartile range = 117.1-258.9µg/L). The median urinary iodine concentrations for pregnant women in 2017 in these areas were 157.7µg/L (interquartile range = 106.9-223.8µg/L), 141.5µg/L (interquartile range = 97.7-207.6µg/L), 127.3µg/L (interquartile range = 90.0-184.5µg/L) and 144.8µg/L (interquartile range = 99.9-184.5µg/L). The median urinary iodine concentrations for lactating women in 2017 in these areas were 122.7µg/L (interquartile range = 84.1–172.0µg/L), 123.7µg/L (interquartile range = 70.7-184.7µg/L), 105.8µg/L (interquartile range = 67.1-152.3µg/L) and 110.2µg/L (interquartile range = 74.1-170.3µg/L). Conclusions The overall urinary iodine concentrations among school-age children, adults and lactating women dramatically decreased after implementing the new standard. Almost all of them were iodine adequate, suggesting we reached the expected aim of iodized salt adjustment. However, pregnant women were iodine insufficient after adjustment. Therefore, we should continue the surveillance of iodine status of populations and focus on the additional iodine supplement strategies for pregnant women.

Iodine nutritional status, the prevalence of thyroid goiter and nodules in rural and urban residents: a cross-sectional study from Guangzhou, China

“…In Guangzhou, the coverage rate of iodized salt was 96.00% of the total population. This result was similar to that obtained in Fujian Province (95.1%), a coastal area near Guangzhou in China [18].…”

“…In Guangzhou, the coverage rate of iodized salt was 96.00% of the total population. This result was similar to that obtained in Fujian Province (95.1%), a coastal area near Guangzhou in China ( 18 ). Interestingly, we found that the coverage rate of iodized salt was significantly higher in rural residents, although they had a much lower median UIC than urban residents.…”

Temporal Trends in Incidence of Nutritional Deficiency among Older Adults in China: A Secondary Analysis of the Global Burden of Disease Study 1990–2019

“…At the time of the 2011 National Iodine Deficiency Disorder survey, 95.3% of households were consuming salt with 20–50 ppm of iodine (the Chinese national standard) [ 27 ]. However, we also noticed a rebound in the incidence rates of iodine deficiency among the female elderly in China from 2004 to 2017, which might be related to the adjustment of decreasing the concentration of iodized table salt in some provinces in recent years [ 28 ]. Moreover, due to changes health consciousness, there was a reduction in salt consumption, especially among women [ 29 ], which might have also resulted in a decline in iodine intake.…”

Effect of Moderate-to-Severe Iodine Deficiency in Early Pregnancy on Subclinical Hypothyroidism: A Longitudinal Study in an Iodine-Sufficient Region in China

“…Mild iodine deficiencies have been reported in most European countries as well as the United States (24,25). Similarly, iodine deficiencies have been widely reported in many regions of China since the implementation of the revised USI standards (15,16,(26)(27)(28)(29)(30). Severe iodine deficiency (UIC lower than 50 µg/L) during pregnancy is associated with maternal and fetal thyroid dysfunction and destructive consequences on fetal intrauterine growth and neurological and cognitive development that can result in miscarriage, stillbirth, and infant mortality (31)(32)(33).…”