To evaluate the operation of urinary iodine external quality control network in Shaanxi Province in 2020, to know the urinary iodine detection capabilities of iodine deficiency disorders (IDD) laboratories in Shaanxi Province, so as to ensure the technical support for epidemiological surveillance and control of IDD.

In 2020, a total of 118 IDD laboratories in Shaanxi Province participated in the external quality control assessment, and the two concentrations of urinary iodine quality control samples were measured by As³⁺-Ce⁴⁺ catalytic spectrophotometry. The testing results of urinary iodine were statistically analyzed with standard value ± uncertainty and Z-ratio scoring methods.

All the 118 laboratories participating in the external quality control assessment of urinary iodine in the province had feedback the assessment results. The standard value ± uncertainty method was used for evaluation, the test results of 118 laboratories in the province were all within the uncertainty range, and all were qualified. The Z-ratio scoring method was used for evaluation, there were two county level laboratories with an inter-laboratory |Z| score≥3, and the evaluation results of other laboratories were all qualified, with a qualified rate of 98.31% (116/118). The results of the two evaluation methods were basically consistent.

After years of external quality control network operation, the urinary iodine detection capability of laboratories at all levels in Shaanxi Province is stable and reliable, and most laboratories have passed the ability verification. It is suggested that individual laboratory should strengthen internal quality control and improve detection capabilities to lay a solid foundation for monitoring and prevention of IDD.

Iodine; Laboratory; Quality control