ESPE Abstracts

Background: Sufficient iodine intake is required for the synthesis of thyroid hormone. Thyroid hormone is very important for normal growth and development, especially in newborn period. It is also well known that excess iodine intake may cause adverse effect in thyroid function.

Objectives and hypotheses: This study was designed to find the iodine status of the newborn with normal thyroid function confirmed by newborn screening of thyroid function test (TFT) and to compare the values with those obtained from the neonates with thyroid dysfunction using random spot urine.

Methods: Newborns in euthyroid were classified as group 1, and the neonates referred for the elevated TSH were classified as group 2. Total 197 urinary samples were collected for the assay of the iodide concentrations in group 1 and 25 urinary samples were obtained from group 2. A P value <0.05 was considered statistically significant using the KESS Software program.

Results: The mean value of urinary iodide was 110.4±165.2 μmol/g Cr in group 1 and 271.0±320.7 μmol/g Cr in group 2 (P<0.05). The free T₄ and TSH levels were also significantly different between two groups (1.59±0.54 vs 1.03±0.52 ng/dl, P<0.001 for free T₄; 1.36±1.10 vs 93.0±145.9 mIU/l, P<0.01 for TSH). The TSH levels showed statistically significant correlation with urinary iodide concentrations in group 2 (r=0.58, P<0.01).

Conclusion: The neonates with thyroid dysfunction showed higher urinary iodide concentrations compared to the neonates with normal thyroid function, suggesting that excess iodine exposure in neonate can contribute to the thyroid dysfunction. It will be worthwhile to check the iodine status as well as TFT for the evaluation of thyroid function in neonates.