Consistent Iodine Status Assessment In Chinese Adults By Different Spot Urinary Iodine Concentrations In A Day Together With Corresponding Correction Coefficients

Objective: The aim of this research was to determine the correction coefficients of different spot urinary iodine concentrations (UICs) in a day to predict the early morning UIC, to make the different spot UICs of a day comparable in assessing iodine status in the same population. Methods: In total, 424 participants aged 18 to 28?years were recruited from Tianjin, China. Three spot urine samples were collected from each participant during three periods of the day (6:30?7:00, 10:00?10:30, and 16:00?16:30). A total of 1272 urine samples were collected. A 24-hour dietary record was reported by each participant for 3 consecutive days. Results: Both the UICs at 10:00?10:30 and 16:00?16:30 were higher than that at 6:30?7:00 (181.75 or 198.15?g/L vs 157.69??g/L; all p??0.05). Bland-Altman plot showed good agreements between the predicted UICs and actual UICs at 6:30?7:00 with both Bland-Altman indexes of 4.5%. Conclusions: It was reliable to predict the early morning UIC using correction coefficients of other spot UIC of the day, which gave a new idea for standardizing the methodology of surveys assessing iodine status of a population.