ABSTRACT
Objective:
To investigate the
iodine nutrition status of residents and its changing trend in Baoji City, Shaanxi Province during the 10 years implementation of a new
salt iodine standard, evaluate the prevention and
treatment effects, and provide a basis for implementing
iodine supplementation
measures scientifically.
Methods:
From 2013 to 2015, each county (district) in Baoji City, Shaanxi Province was divided into 5 districts based on east, west, south, north, and central regions. One town (street, referred to as the town) was selected from each district, and four administrative villages were selected from each town. Fifteen residents from each administrative village were selected to collect edible
salt samples from their homes and test the
iodine content of the
salt. At the same
time, one
primary school was selected from each selected town, and 42
children (age and
gender were balanced)
aged 8 - 10 were selected from each
primary school for
thyroid palpation examination. From 2016 to 2022, each county (district) was divided into 5 districts based on east, west, south, north, and central regions. One town was selected from each district, and one
primary school was selected from each town. Forty-two non boarding
students aged 8 - 10 were selected from each
primary school to undergo
thyroid palpation examination, and edible
salt samples were collected from their home to detect
salt iodine content. At the same
time, 4 administrative villages were selected from each town, and 10 households were selected from each administrative village to collect edible
salt samples and test the
salt iodine content; 21
pregnant women were selected from each of the 5 towns in each county (district) to collect edible
salt samples and test the
salt iodine content. From 2013 to 2022, synchronous collection of
urine samples from
children and
pregnant women (early, middle, and late
pregnancy were balanced) was conducted to detect
urine iodine content. Direct titration
method was adopted for
determination of
salt iodine content, and
arbitration method was adopted for Sichuan
salt and other fortified edible
salt (GB/T 13025.7-1999).
Thyroid examination was performed according to the Diagnostic Criteria for
Endemic Goiter (WS 276-2007).
Urine iodine was detected by
Arsenic Cerium Catalytic Spectrophotometric
Method for
Determination of
Iodine in
Urine (WS/T 107 - 2006).
Results:
From 2013 to 2022, a total of 37 609
household edible
salt samples were collected. The coverage rate of iodized
salt, the qualified rate of iodized
salt and the
consumption rate of qualified iodized
salt for each year ranged from 98.00% to 100.00%, 94.16% to 99.55%, and 92.28% to 99.67%, respectively. The median range of
salt iodine was 22.42 to 26.80 mg/kg. A total of 25 437
children aged 8 - 10 were examined, and the annual
incidence of
thyroid enlargement (
goiter) ranged from 0.35% to 3.02%. A total of 33 270
urine samples were collected, including 21 698 from
children and 11 572 from
pregnant women. The median range of
urine iodine for
children in each year was 203.70 - 275.47 μg/L, median range of
urine iodine in
pregnant women was 167.65 - 218.57 μg/L. The median
urine iodine in
children showed a decreasing trend from 2013 to 2022 ( Z = 3.04, P = 0.002); the median
urine iodine of
pregnant women did not show a significant decrease ( Z = 1.61, P = 0.110).
Conclusions:
During the 10 years implementation of the new
salt iodine standard in Shaanxi Province, all
indicators of
iodine deficiency disorders
monitoring in Baoji City have met the
standards and maintained the elimination status of
iodine deficiency disorders. The
urine iodine levels of
children have shown a downward trend, while
urine iodine levels of
pregnant women do not show significant changes. It is recommended that Baoji City expand the scope of
iodine nutrition monitoring for key
populations, and effectively carry out
iodine supplementation
measures scientificlly guided by
monitoring information, tailored to local conditions, and classified guidance.
