An investigation on iodine nutritional status of children in Yunnan Province before and after adjustment of iodine content in edible salt

Objective To understand the situation of iodine deficiency disorders and iodine nutrition of children in Yunnan Province after the implementation of new standard of salt iodine, and provide the basic data for prevention and control of iodine deficiency disorders. Methods Using multistage sampling method, Yunnan provincial evaluations for iodine deficiency disorders elimination were carried out. According to the comparative analysis of 2010 (pre-adjustment) and 2015 (post-adjustment) evaluation results, the changes of the median of salt iodine, the coverage rate of iodized salt, the qualified rate of iodized salt, the rate of qualified iodized salt consumption, goiter rate of school children aged 8- 10 and the median of urinary iodine were evaluated. iodine was tested using the Salt Industry General Test Method for Determination of (GB/T 13025.7-1999); thyroid volume examination of children using B-scan ultrasonography, thyroid volume calculation and enlargement judgment using Diagnostic Criteria for Endemic Goiter (WS 276-2007); and urinary iodine detection using Urinary Iodine Arsenic Cerium Catalytic Spectrophotometry (WS/T 107-2006). Results The medians of salt iodine in 2010 and 2015 were 30.6 and 22.4 mg/kg, respectively, the difference was statistically significant (U= 317 503.50, P < 0.01). The coverage rates of iodized salt in 2010 and 2015 were 99.6% (1 681/1 688) and 98.9% (2 592/2 622), the qualified rates ofiodized salt were 98.6% (1 657/1 681) and 89.7% (2 325/2 592), and the rates of qualified iodized salt consumption were 98.2% (1 657/1 688) and 88.7% (2 325/2 622), and the differences were statistically significant (χ2= 6.42, 125.11, 130.18, P < 0.01); the rates of children goiter in 2010 and 2015 were 0.8% (25/3 272) and 1.4% (44/3 245), respectively; the medians of urinary iodine of children were 289.0 and 157.3 μg/L, respectively, the difference was statistically significant (U= 1 121 669.50, P < 0.01). Conclusion After decreasing of salt iodine level starting from 2012 in Yunnan Province, the children iodine nutrition condition is in a more proper level. Key words: Iodine; Salts; Urine; Nutrition assessment