Age-specific reference interval of serum TSH levels is high in adolescence in an iodine excess area: Korea national health and nutrition examination survey data.

There was no shift toward higher levels with age in the distribution of serum thyroid-stimulating hormone levels. The reference interval of serum thyroid-stimulating hormone levels was consistently high in all age group, especially from adolescence 10-18 years in a Korean population who had excessive intake of dietary iodine.