Estimation of urinary iodine excretion by iodine/creatinine ratio from morning spot urine in school-age children

Abstract Number Theme Presentation Type Cover Approved
0358 Evaluation of new biomarkers, analytic methods and biological specimens Poster Not Approved


Abstract Content


To evaluate the validity of urinary iodine concentration (UIC) and iodine/creatinine adjustments from spot urines in estimating 24-h urinary iodine excretion (24-h UIE) in school-age children.


A cross-sectional survey in Ningjin and Lingxian Counties, Shandong province, China. Twice repeated 24-h urine and morning spot urine samples were collected from 981 healthy children aged 7-13 years. 24-h UIC, 24-h urinary creatinine concentration (24-h U-Cr), 24-h urinary volume (24-h U-vol), morning spot urinary iodine concentration (MUIC) and morning spot urinary creatinine concentration (MU-Cr) were measured in all samples. Measured 24-h UIE was calculated by 24-h UIC multiplying 24-h U-vol, while estimated 24-h UIE was calculated by morning spot urinary iodine/creatinine ratio (MUI/Cr) multiplying 24-h urinary creatinine excretion (24-h UCrE).


No significant differences were observed in the morning spot urine iodine/creatinine ratio (MUI/Cr), 24-h UIC and measured 24-h UIE between twice repeated collections. The MUI/Cr was significantly lower than 24-h urine iodine/creatinine ratio (24-h UI/Cr) in both collections, and the estimated 24-h UIE was lower than measured 24-h UIE as well. Measured 24-h UIE and estimated 24-h UIE were significantly correlated with age. However, no differences were observed in 24-h UIC and MUIC among different ages. In addition, MUI/Cr, 24-h UI/Cr and estimated 24-h UIE were strongly correlated with measured 24-h UIE.


Iodine/creatinine adjustments from spot urine could be a valid and reliable alternative to the measured 24-h UIE in evaluating individual iodine intake, but UI/Cr adjustments from morning spot urine may underestimate urinary iodine excretion in school-age children.

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