The paper summarizes hitherto assembled knowledge on the mechanistu of iodine penetration finto cells and its direct action in tissues of the thyroid gland, placenta, mammary gland and gastric mucosa. It deals in more detail with indirect effects of iodine in the form of thyroid hormones on the development of the CN5 in early life, on growth and development and interhormonal harmony during the adolescent period. It emphasises the importance of transplacental transmission of iodine and the role of maternal thyroxine. It mentions the minimal daily iodine requirement for different age groups as defined by WHO. The author reflects also on the present situation as regards iodine supplies of our population as evaluated by the National Iodine Commission, and in the conclusion recommends preventive, diagnostic and therapeutic procedures which can be used in particular in ambulatory practice of general practitioners for children but not only there.

        Key words: Na/I symporter, ioduria, placental transfer, maternal hypothyroxinaemia, daily intake, risk groups of the population, diagnosis