Iodine Status and Its Influencing Factors in Hospitalized and Healthy Preschool-Age Children

Iodine is a trace element necessary for synthesizing thyroid hormones. It is especially crucial for the neurodevelopment and intellectual development of children. Preschool-age children admitted to the hospital tend to have more fragile physical and mental health, but few studies demonstrate their iodine status. Our study aimed to investigate the iodine status of hospitalized and healthy preschool-age children and to explore the factors influencing them. From January to December 2021, 426 children aged 3–6 years were admitted to the respiratory department for pneumonia, bronchopneumonia, or bronchiectasis, but they could eat normally and were recruited as hospitalized children. Six hundred ten healthy children aged 3–6 years were included. We collected anthropometric measurements and urine samples from hospitalized and healthy preschool-age children, and iodine status was assessed through urinary iodine concentration (UIC) and urinary iodine/creatinine ratio (UI/Cr). UIC was 40.1 and 166.1 µg/L for hospitalized and healthy preschool-age children, respectively (P < 0.001). Urinary creatinine concentration (UCr) was 0.2 and 0.8 g/L for hospitalized and healthy preschool-age children, respectively (P < 0.001). UIC decreased with increasing height z-scores in hospitalized children (Spearman's rho = −0.11, P = 0.022). A significantly increased risk of UIC < 100 µg/L was found in hospitalized children (OR = 9.1 (6.8, 12.2), P < 0.001) when compared to healthy children. In conclusion, hospitalized preschool-age children are likelier to have iodine insufficiency than healthy preschool-age children, especially those with good linear growth. Measures should be implemented to ensure adequate iodine intake of preschool-age children during hospitalization to avoid affecting their intellectual and physical development. Due to lower UCr in hospitalized children, creatinine is not appropriate for assessing iodine status in hospitalized children.