title: Control of iodine-deficiency disorders following universal salt iodization in Shenzhen, China, 1997-2011.
abstract: BACKGROUND
  Since universal salt iodization (USI) was implemented in Shenzhen, China, in 1996, evaluation of the time trend of USI to indicate the control of iodine-deficiency disorders has not been performed.
  
  
  OBJECTIVE
  To assess the time trend of median urinary iodine and total goiter rates from 1997 to 2011.
  
  
  METHODS
  Probability-proportionate-to-size sampling was employed in the surveillance of iodine-deficiency disorders, for which schoolchildren aged 8 to 10 years were randomly selected from five districts of the city during each iodine-deficiency disorders survey. Urinary iodine content and thyroid size were measured by ammonium persulfate oxidation and B ultrasound, respectively.
  
  
  RESULTS
  The coverage of iodized salt increased from 73.2% in 1997 to more than 90% in 2011. The median urinary iodine of children aged 8 to 10 years varied between 207.1 and 278.8 microg/L; these levels were above the urinary iodine level in 1995. The proportion of urine samples with iodine content above 300 microg/L was 45.6% in 1997 and decreased to 20.8% in 2011, indicating excessive consumption of iodine by the children. The goiter rate among children dropped from 10.8% in 1997 to 1.3% in 2011; both values were lower than the goiter rate in 1995, indicating that the spread of endemic goiter was under control.
  
  
  CONCLUSIONS
  Preliminary elimination of iodine-deficiency disorders was achieved by USI in Shenzhen. Nevertheless, some problems still existed, such as over-iodization. To clarify the causes of excessive urinary iodine content, the various sources of iodine from the diet need to be investigated in the future.
authors.affiliation: Shenzhen Center for Disease Control and Prevention, Shenzhen, Guangdong, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Chaoqiong
authors.initials: C
authors.lastname: Peng
authors.forename: Haixiong
authors.initials: H
authors.lastname: Huang
authors.forename: Jinzhou
authors.initials: J
authors.lastname: Zhang
authors.forename: Jianping
authors.initials: J
authors.lastname: Liu
authors.forename: Lisha
authors.initials: L
authors.lastname: Mao
authors.forename: Ruorong
authors.initials: R
authors.lastname: Luo
authors.forename: Yunjun
authors.initials: Y
authors.lastname: Xiao
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000652:urine; D002648:Child; D002681:China / Q000453:epidemiology; D005260:Female; D006043:Goiter, Endemic / Q000453:epidemiology / Q000517:prevention & control* / Q000652:urine; D006293:Health Promotion / Q000379:methods / Q000706:statistics & numerical data; D006801:Humans; D007455:Iodine / Q000008:administration & dosage / Q000172:deficiency* / Q000652:urine; D008297:Male; D009929:Organ Size; D011159:Population Surveillance / Q000379:methods; D015397:Program Evaluation / Q000379:methods / Q000706:statistics & numerical data; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage*; D013961:Thyroid Gland / Q000000981:diagnostic imaging; D014463:Ultrasonography; D014505:Urban Population / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D015415:Biomarkers; D017673:Sodium Chloride, Dietary; C034024:iodized salt; D007455:Iodine