Study on the rhythm of urine iodine level of children aged 8-10 in Chongqing city

Objective To undemtand the rhythm of urinary iodine level of children aged 8-10 in Chongqing city.Methods In April 2008,using the stratified random sampling method,we sampled 60 children aged 8-10 in a lodging primary school in Chongqing(20 per age group,half male and half female),the urine samples were collected in the morning and at 10:00,12:30,16:00,iodine in urine was detected by method of Ce and arsenic catalytic speetrophotometry(WS/T 107-2006).The difference of the urinary iodine level was compared by age,sex and time of day.Results The median urinary iodine of 60 children was 265.07μg/L on the overall.Irrespective of the stratification factors,excluding morning urinary iodine(366.75μg/L)and urinary iodine at 10:00(338.30 μg/L),the urinary iodine between 12:30(235.15μg/L)and 16:00(251.50μg/L)was not significant(all P>0.05),statistically significant differences(all P 0.05).The 9-year-old group's urinary iodine were not significantly different between morning urine(366.15μg/L)and 10:00(368.10 μg/L),and between 12:30(244.00 μg/L)and 16:00(186.30 μg/L,all P>0.05),significant differences were faund at other times of the day(all P 0.05 ), followed by rapid decline to 16: 00 (269.35 μg/L), and compared with the morning urine and 10:00, there was significant difference(all P 0.05). Conclusions The change of urinary iodine level in children aged 8 - 10 was not obvious before noon, changes can be seen in the afternoon.Urinary iodine level before 10:00 is indicative. Key words: Iodine; Urine; Rhythm