Why is povidone-iodine not safe for neonates/premature infants but can be used on mature infants?

• A. It is more effective when used on neonates
• B. It causes renal toxicity
• C. It may be absorbed resulting in thyroid dysfunction
• D. It is cheaper than alternatives

Answer: (C)

Povidone-iodine can be absorbed through the skin, and newborns have skin that is thin and more permeable with a high surface area-to-body weight ratio. In neonates, especially premature infants, the thyroid system and kidney function are immature, so a larger proportion of the absorbed iodine enters the body and isn’t cleared quickly. The sudden iodide load can push the thyroid into a dysregulated response (the Wolff-Chaikoff effect), which can transiently suppress thyroid hormone production and cause thyroid dysfunction. Because the thyroid in these infants is still developing, they’re particularly vulnerable to this disruption. As infants grow and their skin barrier matures and their thyroid autoregulation and renal clearance improve, they can tolerate lower levels of iodine exposure better, making the same antiseptic safer in older babies. The risk here centers on thyroid impact from iodine absorption, not on renal toxicity or cost, which is why the correct choice emphasizes potential thyroid dysfunction from absorbed iodine.