Hypothyroidism and Iodine Deficiency in Children on Chronic Parenteral Nutrition

BACKGROUND AND OBJECTIVES: Iodine is an essential trace element for maintenance of normal thyroid function. Normal thyroid function is a prerequisite for neurocognitive development and growth in children. In the United States, iodine is not routinely added as a trace element in parenteral nutrition (PN). Our objective was to determine the prevalence of iodine deficiency and hypothyroidism in children on chronic PN. METHODS: This was a cross-sectional study of children 6 months at a tertiary children’s hospital. Primary outcomes were spot urine iodine concentration (UIC), serum thyrotropin, and free thyroxine levels. RESULTS: Twenty-seven patients were identified (74% male). The median age at screening was 48 months (range: 7–213 months). The median duration on PN was 27 months (range: 11–77 months). Seventeen out of 20 patients (85%) were iodine deficient (spot UIC n = 8). None of the children with hypothyroidism screened for autoimmune thyroiditis had positive test results. There was no statistically significant association between duration of PN use and development of iodine deficiency ( P = .08) or hypothyroidism ( P = .96). CONCLUSIONS: Children on chronic PN are at risk for developing iodine deficiency and resultant hypothyroidism; hence, these children should be screened for these outcomes. Further studies are needed to define the temporal onset of iodine deficiency and timing to thyroid dysfunction related to PN.