Objective To understand the pathway of iodine intaking among Tibetan, and provide basic data for prevention and control of iodine deficiency disorders (IDD). Methods Through the method of random sampling, the boarding and day student aged 8 - 10 and women of childbearing age were conducted dietary survey to understand the condition of food intaking via the 24 h review method in 2015. Samples of urine, drinking water, dried beef, milk, Qula and fried noodles were collected and tested iodine level. Results Due to taking iodized salt three times a day with meals, the median of urinary iodine among 492 investigated boarding students was 179.2 μg/L;differently, the median of urinary iodine among 298 day students in this investigation was 79.6 μg/L who taking iodized salt only at lunch at school;and in the study, the median of urinary iodine among 158 women of childbearing age who took iodine-free salt daily was 33.7 μg/L. The iodine contents in 51 drinking water samples, 66 dried beef samples, 48 milk samples, 20 Qula samples and 37 fried noodle samples were quantified respectively, and the average iodine contents of each food were 0.8 μg/L in drinking water, 59.1 μg/kg in dried beef, 61.5 μg/kg in milk, 226.4 μg/kg in Qula and 17.0 μg/kg in fried noodles. The acceptable daily intake (ADI) of iodine of the boarding and day students aged from 8 to 10 and women of child bearing age were 234.0, 126.4 and 76.7 μg/d, respectively, among which the ADI of iodine with iodized salt were 208.0, 78.0 and 0.0 μg/d. Conclusion Consuming iodized salt is a main method to get iodine among Tibetans in Nangqian County, so that it is significant to carried out this measure for a long time for free to let them have iodized salt every day instead of iodine-free one.

Objective:To investigate the dietary iodine intake of people in different areas of Qinghai Province, and to provide the basis for scientific iodine supplementation and continuous elimination of iodine deficiency hazards.Methods:From 2018 to 2019, according to administrative division, natural geographical regions, population distribution and economic development level of Qinghai Province, a total of 14 survey sites were selected. One village was selected from each survey site, and 20 households were selected from each village, the salt samples and 24 h urine samples of all family members were collected to detect salt iodine and urinary iodine. One drinking water sample was collected at the five directions of east, west, south, north and middle of each village to detect water iodine. Salt iodine was detected by direct titration, urinary iodine and water iodine were detected by arsenic-cerium catalytic spectrophotometry. At the same time, the 3-day weighing method was used to investigate the diet, the daily dietary iodine intake per capita (the result was expressed as average) and the proportion of dietary iodine in urinary iodine were calculated, the daily dietary iodine intake per capita of different production modes (agricultural region and pastoral region), different geographical environment (Hehuang Valley, Qaidam Basin, Qilian Mountain and Qingnan Plateau), different nationalities (Han, Tibetan, Hui, Mongolian, Tu, Salar) and different economic levels (< 8 000, 8 000 -, 10 000 -, ≥12 000 Yuan) were compared.Results:A total of 999 people from 280 families were surveyed, including 511 males and 488 females. The median water iodine of each survey site was less than 10 μg/L, all of which were environmentally iodine-deficient areas. A total of 280 salt samples were collected, the median salt iodine was 26.0 mg/kg, and the consumption rate of qualified iodized salt was 100% (280/280). A total of 999 urine samples were tested, and the median urinary iodine of people was 192.5 μg/L, which was at an appropriate level of iodine. There was no statistically significant difference ( t =-1.599, P > 0.05) in the daily dietary iodine intake per capita (28.53, 33.44 μg) of people in agricultural region ( n = 643) and pastoral region ( n = 356). The daily dietary iodine intake per capita (25.38, 33.30, 32.98, 34.79 μg) of people in Hehuang Valley ( n = 448), Qaidam Basin ( n = 125), Qilian Mountain ( n = 157), and Qingnan Plateau ( n = 269) were compared, the difference was statistically significant ( F = 2.883, P < 0.05); among them, the daily dietary iodine intake per capita in Hehuang Valley was lower than that in Qingnan Plateau ( P < 0.05). The daily dietary iodine intake per capita of different nationalities were compared, the difference was statistically significant ( F = 3.647, P < 0.05), Salar ( n = 68) and Tibetan ( n = 239) were higher (37.21 and 32.21 μg). The daily dietary iodine intake per capita (38.97, 17.01, 30.86, 33.14 μg) of annual per capita disposable income < 8 000 ( n = 194), 8 000-( n = 221), 10 000-( n = 302), ≥12 000 Yuan ( n = 282) were compared, the difference was statistically significant ( F = 9.407, P < 0.05). The proportions of dietary iodine in urinary iodine of various population ranged from 5.35% to 15.54%. Conclusions:The iodine nutrition of people in Qinghai Province is suitable, the dietary iodine intake of people is closely related to geographical environment, nationality and economic level. But the proportion of dietary iodine in urinary iodine is relatively low, the consumption of iodized salt is still the main way for people to intake iodine, and it is also the main measure to continuously eliminate the harm of iodine deficiency in Qinghai Province.

Objective:To verify the revised method of cerium sulfate catalytic spectrophotometry for iodide index of "Standard Examination Methods for Drinking Water-Nonmetal Parameters" (GB/T 5750.5-2006).Methods:From July to September 2019, the Laboratory of Department for Endemic Disease Prevention and Control of Qinghai Institute for Disease Prevention and Control verified the revised method (determination of iodide in drinking water by cerium sulfate catalytic spectrophotometry) of cerium sulfate catalytic spectrophotometry (hereinafter referred to as original method) in "Standard Examination Methods for Drinking Water-Nonmetal Parameters" (GB/T 5750.5-2006). The revised method was verified according to the requirements of "Standard Examination Methods for Drinking Water-Water Analysis Quality Control" (GB/T 5750.3-2006), including standard curve, detection limit, precision, accuracy and actual sample determination.Results:The linear range of the revised method was 0 - 20.0 μg/L, the correlation coefficient was - 0.999 4 - 0.999 8, and the detection limit was 0.231 μg/L. The relative standard deviation ( RSD) of low, medium and high iodine water samples of 6 times detection ranged from 1.4% to 9.6%, and the recoveries of low and medium water samples ranged from 89.0% to 108.0%. The detection results of national first-class reference materials for iodine composition analysis in water were within the range of standard value ± uncertainty. There was no significant difference in the test of results of 12 tap water samples between the revised method and the original standard method ( t = - 0.075, P > 0.05). Conclusion:The revised method has a good linear relationship of standard curve, high precision and accuracy, and good reproducibility, is simple and easy to operate, and is suitable for promotion and application.

Objective To investigate the relationship between thyroid volume and multiple body indexes such as urinary iodine level,height,and weight,respectively,in order to provide a theoretical basis for evaluation of goiter disease in the future. Methods The height and weight were measured, and urine samples were collected from children aged 8 to 10 years old from 10 township schools of Nangqian County in Qinghai Province in 2014 and urinary iodine was tested via the As (Ⅲ)-Ce4+catalytic spectrophotometry method. Meanwhile, the thyroid volume was immediately measured via the B-ultrasound method. Statistical analyses were employed finally to assess the difference and correlation between thyroid volume and multiple physiological indexes including urinary iodine level, height, weight, gender and age. Results The thyroid volume of 773 children aged 8 to 10 years old showed skewed distribution (W = 0.088, P < 0.05), with median of 3.53 ml and quartile of 3.05, 4.15 ml. The thyroid volume was not significantly different between different urinary iodine levels (H = 1.644, P > 0.05). There were significant differences of the thyroid volume among different height groups, weight groups and age groups (H=59.845,64.888,28.590,P<0.05),and the thyroid volume was positively correlated with height weight and age,respectively(r = 0.389, 0.359, 0.155, P < 0.05). Conclusions The thyroid volume is related to the level of children's physiological parameters, such as age, height, weight. Therefore, the diagnosis of thyroid volume via the B-ultrasound method for a individual child should not only take age,but also height and weight into account, to reduce the diagnostic error of goiter disease.

Objective To detect urinary bio-markers of hydroxyproline (HYP) and c-terminal telopeptide of collagen type Ⅱ (CTX-Ⅱ) among population from Kashin-Beck disease (KBD) regions in Qinghai Province,and to provide the scientific data for prevention and control of adult KBD.Methods According to the "Diagnosis of Kashin-Beck Disease" (WS/T 207-2010),using case-control study,120 KBD patients (males 55,females 65) and 89 healthy controls (males 41,females 48) in Qinghai KBD regions were divided into case group and control group.Morning urine samples were collected.HYP and CTX-Ⅱ contents were analyzed by enzyme-linked immunosorbent assay (ELISA),then these results were corrected with creatinine.All the data were analyzed by SPSS 17.0 software.Results There was no significant difference in the age of male and female between case group and control group (t =1.813,1.131,P ＞ 0.05).The medians of urinary HYP and CTX-Ⅱ contents among male patients were 74.91 μg/μmol Cr and 630.77 ng/μmol Cr,respectively,which were higher than those of control groups (51.38 μg/μ mol Cr,401.32 ng/μmol Cr,Z =3.068,3.246,P ＜ 0.01).The medians of urinary HYP and CTX-Ⅱ contents among female patients were 91.07 μg/μmol Cr and 637.17 ng/μmol Cr,respectively,compared with those of control groups (88.37μg/μmol Cr,546.47 ng/μmol Cr),there was no significant difference in HYP content (Z =0.273,P ＞ 0.05),however,the difference in CTX-Ⅱ content was statistically significant (Z =2.002,P ＜ 0.05).Conclusion The urinary HYP contents of male patients with KBD change significantly,while the degradation of type Ⅱ collagen in male and female patients increases,and CTX-Ⅱ could reflect the metabolic changes of collagen in KBD.

Objective:To analyze the assessment results of the external quality control in iodine deficiency disorders laboratories at all levels in Qinghai Province so as to provide quality assurance for monitoring and control effect evaluation of iodine deficiency disorders.Methods:The results of urinary iodine, salt iodine, and water iodine quality control assessments at the provincial, city (state) and county-level iodine deficiency disorders laboratories were analyzed in Qinghai Province from 2013 to 2018 (sourced from the annual evaluation results issued by National Reference Laboratory for Iodine Deficiency Disorders). Among them, there were 1 provincial, 8 city (state) and 43 county-level (2017, 2018) laboratories participated in the urinary iodine assessment; 1 provincial, 8 city (state) and 30 county-level (43 in 2017 and 2018) laboratories participated in the salt iodine assessment; 1 provincial and 8 city (state)-level laboratories participated in the water iodine assessment.Results:From 2013 to 2018, the feedback rates and qualified rates of provincial and city (state)-level laboratories participated in the urinary iodine external quality control assessment were 100.0%; the feedback rates of 43 county-level laboratories (2017 and 2018) were 100.0%, and the qualified rates were 93.0%(40/43) and 88.4%(38/43), respectively. The feedback rates and qualified rates for salt iodine assessment in provincial and city (state)-level laboratories were 100.0%; the county-level laboratories feedback rates were 100.0%, and the qualified rates were > 90.0% except for 2014. And the feedback rates of provincial and city (state)-level laboratories for water iodine assessment were 100.0%; the qualified rate of provincial-level laboratory was 100.0%, and the city (state)-level laboratories were 100.0% except 2016 (7/8).Conclusions:The quality control network of Qinghai Province's iodine deficiency disorders laboratories has fully covered all city (state) and county-level laboratories. Provincial, city (state)-level laboratories have stable and reliable levels of urinary iodine, salt iodine, and water iodine; some individual county-level laboratories testing capabilities still need to be improved.

Objective:To analyze the results of serum erythropoietin (EPO) in adults patients with Kaschin-Beck disease (KBD) in Qinghai Province.Methods:According to the "Diagnosis of Kaschin-Beck Disease" (WS/T 207-2010), by using clinical examination and X-ray, adults over 20 years old in KBD areas of Xinghai County and Guide County, Hainan Tibetan Autonomous Prefecture, Qinghai Province, were divided into KBD case group ( n = 109) and internal control group ( n = 95) in July 2019. At the same time, healthy people were selected as external control group ( n = 90) in Xunhua County. Then 2 ml fasting cubital venous blood was collected from the target population to separate serum. The serum EPO level was determined by enzyme-linked immunosorbent assay (ELISA). Results:There was no significant difference in age and sex ratio among the 3 groups ( F = 0.73, P = 0.484; χ 2 = 1.03, P = 0.611). There was significant difference in serum EPO levels among the 3 groups [KBD case, internal and external control groups: (30.74 ± 26.23), (19.73 ± 11.53) and (10.83 ± 4.48) U/L, F = 26.51, P < 0.001]. Multiple comparisons showed that there were statistically significant differences in serum EPO levels between KBD case group and the internal and external control groups ( P < 0.05), but there was no significant difference between the internal and external control groups ( P > 0.05). Conclusions:The serum EPO level in adult KBD patients in Qinghai Province is increased significantly.

Objective:To understand the water iodine content in Qinghai Province and draw a distribution map of water iodine, so as to provide a basis for scientific supplementation of iodine and continuous elimination of iodine deficiency hazards.Methods:In 2017, in all counties (cities, districts) in Qinghai Province, with townships (towns, streets, referred to as townships) as the unit, the residents' drinking water samples were collected, water iodine content was tested, the median water iodine was calculated, and the water iodine distribution map of Qinghai Province was drew.Results:Totally 1 836 drinking water samples were collected in 392 townships, the median water iodine was 1.7 μg/L. Townships that had the median water iodine < 5 μg/L, in the range of 5 to 10 μg/L and > 10 μg/L accounted for 80.6% (316/392), 17.1% (67/392) and 2.3% (9/392), respectively. Among all townships, the highest of the median water iodine was 24.8 μg/L. Based on the results, water iodine distribution map of Qinghai Province, water iodine distribution map of Xining City and water iodine distribution map of Haidong City were compiled.Conclusions:Iodine deficiency is widespread throughout natural environment in Qinghai Province. Hence, salt iodization measures to prevent iodine deficiency disorders should be implemented continuously. According to the water iodine distribution map, the people should be guided to supplement iodine scientifically.

Objective:To analyze the external quality control assessment results of fluoride in brick tea in the provincial, city (prefecture) and county (city, district)-level endemic fluorosis laboratories in Qinghai Province, and to evaluate the testing capabilities of laboratories at all levels.Methods:The Z-score method was used to analyze and evaluate the results of provincial, city (prefecture) and county (city, district)-level laboratories that participated in the external quality control assessment of fluoride in brick tea in Qinghai Province from 2014 to 2020, and│Z│≤2 was qualified; 2 <│Z│ < 3 was basic qualified; │Z│≥3 was unqualified.Results:From the feedback, the feedback rate of external quality control of fluoride in brick tea in provincial and city (prefecture)-level laboratories in Qinghai Province from 2014 to 2020 was 100.00%; the feedback rate of county (city, district)-level laboratories from 2014 to 2018 was 100.00%, and there were no feedback units in 2019 and 2020. From the assessment of qualification, the qualification rate of provincial, city (prefecture)-level laboratories was 100.00% in all other years except one unit failed in 2017; the qualification rate of county (city, district)-level laboratories was 100.00% in 2014, 2015, 2016 and 2019, and there were 6 unqualified units in other years.Conclusions:From 2014 to 2020, some endemic fluorosis laboratories in Qinghai Province still fail to pass the external quality control assessment of fluoride in brick tea. In the future, it will be the focus of work to strengthen personnel training and improve the detection ability.