Analysis of field survey results for iodine deficiency disorders in high-risk areas of China / 中国地方病学杂志

ABSTRACT

Objective To investigate the occurrence of new cretinism cases and the prevalence of endemic goiter, and the reason of lower coverage rate of iodized salt in the iodine deficiency disorders(IDD) high-risk areas of China, so as to put forward target prevention measures for these areas. Methods A hundred and one counties from 11 provinces(autonomous regions, municipality), such as Tibet, Qinghai, Xinjiang, Gansu, Ningxia, Sichuan, Hainan, Chongqing, Yunnan, Guangxi, Inner Mongolia, were chosen into the survey by simple random sampling. In the counties of high risk, typical sampling principle was used. In the selected townships, searching for new cretinism cases were carried out in the children under 10 years old, the thyroid volume of children aged 8-10 years old were determined by B-ultrasonography methods and their urinary iodine (UI) were determined by As3-Ce<'4+> catalytic spectrophotometry, the intelligence quotient(IQ) values of children aged 8-10 years old were measured by the combined Raven Test in China. In the household survey, the housewives were asked to fill in the questionnaire, the iodized salt coverage rates and the UI levels of child-bearing age women were investigated, the salt iodine content was determined using self-quantitative kit. Epi Info software was used to analyze the determination results. Results In the 101 high-risk counties, 249 were diagnosed as new cretinism cases from 4122 suspected cases searched. The goiter rate of children aged 8-10 years old by B-ultrasound was 8.28% (4434/53 541), 44 counties had goiter rates in the range of 5%-20%, 5 counties had goiter rates in the range of 20%-30%, and 3 counties had goiter rates of 30%. The mean IQ of children was 85.44, and the percentage of IQ value less than 70 was 16.52%(8713/52 745). The median urinary iodine(MUI) of children was 154.69 μg/L, the percentage of UI less than 50 μg/L was 17.26% (9069/52 558). Twenty-five counties had a MUI of children less than 100 μg/L. The MUI of housewives was 107.14 μg/L, the percentage of UI less than 50 μg/L was 27.50% (3722/13 534). MUI of housewives in 46 counties were less than 100.0 μg/L. The coverage rate of iodized salt at household level was 77.85%(13 150/16 891). The coverage rate of iodized salt was 52.80%(1585/3002), 44.72% (631/1411) and 72.82% (1850/2506) in Tibet, Hainan and Qinghai, respectively. More than 10% residents of Tibet, Sichuan, Hainan, Gansu and Qinghai complained that iodized salt was not convenient to buy. There were 71.39%(7652/10 719) of observed people ate crude salt. The average price of crude salt price(0.30-1.20 Yuan/kg) was lower than iodized salt(1.20-3.00 Yuan/kg). Conclusions In these IDD high-risk areas, the risk of endemic goiter and cretinism prevalence is threatening. The IDD monitoring should be carried out successively in these high-risk areas. The prevention measures, increasing iodized salt coverage rate and establishing the sustainable mechanism for eliminating IDD should be strengthened. Emergent iodine fortification measure for high risk region people should be implemented as soon as possible, a long term effective mechanism of eliminating IDD should be established.