The application value of estimating 24 h urinary iodine excretion in the evaluation of individual iodine nutrition level / 中华地方病学杂志

ABSTRACT

Objective:To explore the application value of creatinine correction method in estimating 24 h urinary iodine excretion of healthy adults.Methods:Healthy adults(half males and half females) aged 18 to 59 yesrs old in Tangshan City were selected as the research subjects. Random urine within 1 d, morning urine and 24 h urine samples of 5 d in a row of all subjects were collected to detect urinary iodine and creatinine concentrations. Twenty-four hours urinary iodine excretion was estimated by creatinine correction formula [24 h urinary iodine excretion estimated value(μg/d) = urinary iodine/creatinine concentration ratio (μg/g Cr) × 24 h urinary creatinine excretion (g Cr/d)]. The estimated value of 24 h urinary iodine excretion obtained from random urine within 1 d and continuous 5 d morning urine corrected by creatinine were studied by the coefficient of variation, and compared with the measured value of 24 h urinary iodine excretion.Results:The coefficient of variation of the estimated 24 h urinary iodine excretion of random urine within 1 d ranged from 8.8% - 20.2%, with an average value of 13.1%; the coefficient of variation of 24 h urinary iodine excretion estimated value from continuous 5 d morning urine and the 24 h urinary iodine excretion measured value ranged from 4.7% - 17.2% and 4.0% - 10.4%, and the average values were 10.1% and 6.4%, respectively. In the detection of random urine within 1 d, there was no significant difference between the 24 h urinary iodine excretion estimated value of the first, second, third, and forth time random urine and the 24 h urinary iodine excretion measured value ( P > 0.05). In the detection of continuous 5 d morning urine, there were no significant differences in the 24 h urinary iodine excretion estimated value of the first, second, third, forth and fifth day compared with the 24 h urinary iodine excretion measured value on the same day, respectively ( P > 0.05). Conclusions:When the daily creatinine excretion is accurately known, the estimated 24 h urine iodine excretion obtained by the creatinine correction method can better reflect the actual 24 h urinary iodine excretion. Further study on prediction criteria of creatinine excretion suitable for Chinese people will help to better detect the iodine intake of corresponding individuals.