Objective To monitor the situation of iodine deficiency disorders (IDD) in Tibet,and to provide a background information of iodine nutritional status of residents before adjustment of iodine concentration.Methods According to the method of population proportionate sampling (PPS),27 counties were selected to carry out IDD surveillance.One primary school was selected in each county.Forty children aged 8-10 from each primary school were sampled to examine thyroid volume,and edible salt samples were collected from their home to determine salt iodine.In addition,12 of the sampled children,15 pregnant women and 15 lactating women from three townships near the selected schools were chosen to detect urinary iodine.The methods of B-ultrasonography,oxidation-reduction titration (GB/T 13025.7-1999) and arsenic cerium catalytic spectrophotometry (WS/T 107-2006) were used to determine thyroid volume,salt iodine and urinary iodine,respectively.Results One thousand and eighty-one children aged from 8 to 10 were examined,and their goiter rate was 1.9％ (20/1 081).Seven hundred and fifty-eight salt samples were determined,and the median salt iodine level was 38.3 mg/kg and the consuming rate of qualified iodized salt was 88.1％(758/668).Meanwhile,urine samples of 522 children aged 8-10,267 pregnant women and 336 lactating women were also tested,and their median urinary iodine level was 166.1,132.7,138.1 μg/L,respectively.Conclusions The results show that the goiter rate and urinary iodine level of children aged from 8 to 10 have reached the national standard of IDD elimination (＜5％,100-300 μg/L),while the residents consumption rate of qualified iodized salt is still lower than the national standard (90％).In particular,the iodine nutrition of pregnant women is inadequate,which is lower than the national standard (urinary iodine 150 μg/L).It is still necessary to strengthen the monitoring of salt iodine as well as iodine nutrition in special groups in the future,and strengthen health promotion at the same time.

Objective:To understand the iodine nutritional status of Tibet residents and provide a scientific basis for prevention and treatment of iodine deficiency disorders in Tibet.Methods:A cross-sectional survey was conducted in 67 counties (districts) of 7 cities of Tibet. Each county (district) was divided into 5 sampling areas according to its east, west, south, north and middle location, and 1 township (town) was selected from each sampling area. Four administrative villages were selected from each township (town), and 15 household's salt samples were sampled for salt iodine detection. Twenty pregnant women and 1 primary school were selected from each township (town). Forty non-boarding children aged 8-10 years (half male and half female) were selected from each primary school, urine samples were collected for urinary iodine detection. Thyroid volume was also measured in children aged 8 to 10 years in 3 cities.Results:In 2018, the median of salt iodine in Tibet was 25.33 mg/kg (22 136 samples). The coverage rate of iodized salt, the qualified rate of iodized salt and the consumption rate of qualified iodized salt were 97.75% (21 637/22 136), 87.00% (18 824/21 637) and 85.04% (18 824/22 136), respectively. The difference between 7 cities were statistically singnificant ( P < 0.01). Naqu City had the lowest levels [92.03% (2 923/3 176), 69.41% (2 029/2 923), 63.89% (2 029/3 176)]. The median of urinary iodine of 13 516 children aged 8-10 years was 187.0 μg/L. The urinary iodine of boys was 188.6 μg/L, girls was 185.6 μg/L. The median of urinary iodine of 2 920 pregnant women was 165.6 μg/L. The differences in urinary iodine of pregnant women in different pregnancy periods were statistically significant ( H=13.33, P < 0.01). The urinary iodine of pregnant women was the highest in early pregnancy (178.9 μg/L) and the lowest in late pregnancy (162.3 μg/L). The goiter rate of children aged 8-10 years was 1.01% (34/3 364). The goiter rate of children in different cities was different (χ 2=59.28, P < 0.01), and Changdu had the highest (4.25%, 17/400). Conclusions:In 2018, the consumption rate of qualified iodized salt among Tibet residents is relatively low, and the comprehensive prevention and control measures of iodine deficiency disorders need to be further strengthened. We should strengthen the monitoring of iodine nutrition level of pregnant women at different stages of pregnancy, strengthen health education and raise the awareness of prevention and treatment of iodine deficiency disorders among residents.

Objective To explore the status of iodine nutrition and iodine deficiency disorders in the pasturing areas and agricultural regions in Tibet. Methods 30 families were selected respectively in pastoral Dangxiong county and agricultural Qushui county of Lasa. Drinking water and edible salt were collected for testing the iodine contents. In each type of the following populations including children aged 8-10, women of child-bearing age and male adults, 50 subjects were randomly sampled to examine their urinary iodine contents. Among them, 50 children and 50 women were randomly selected for goiter examination by palpation. Results Water iodine content was less than 2μg/L, both in pasturing area and in agricultural areas. There was no iodized salt used in the families of pasturing areas, while 90% people consumed iodized salt in agricultural areas. The median of urinary iodine in pasturing area was 50.2 μg/L, significantly lower than that of agricultural area (193.2μg/L). However, the goiter rate of children and women in pasturing area was significantly lower than that in agricultural area. Conclusion Although iodine intake of populations in pasturing area of Tibet was severely deficient, there was no epidemic of Iodine Deficiency Disorders. This phenomenon noticed by the researchers deserved further investigation.