In Chinese children between 7 and 14 years old, consuming iodine at levels of 250–399 micrograms per day is linked to a higher likelihood of developing an enlarged thyroid gland, with higher intake levels corresponding to greater risk.

In children aged 7–14, the size of the thyroid gland and the presence of goiter are better signs of thyroid stress caused by too much iodine over time than blood levels of thyrotropin or thyroglobulin, because they change more consistently with the amount of iodine consumed.

Scientists have noticed that people who consume more iodine sometimes have a higher risk of goiter, so they suggest maximum daily iodine intake levels of 250 micrograms for children 7–10 years and 300 micrograms for children 11–14 years, but these levels have not been shown to prevent goiter.

In children with a specific genetic mutation (DUOX2) and mild thyroid underactivity not caused by autoimmunity, taking iodine supplements within the range of 50–150 micrograms per day does not bring thyroid hormone levels back to normal, because thyroid-stimulating hormone (TSH) stays high.

In children aged 7 to 14, elevated TSH levels are common and stay above 10% regardless of whether iodine intake is 200–300 micrograms per day or higher, indicating that TSH levels alone cannot reliably signal too much iodine in this group.

In children with a mild form of congenital hypothyroidism and an intact thyroid gland, giving iodine supplements does not change how their thyroid function develops over time, based on measurements taken after stopping iodine and during one year of monitoring.