Salt iodization in Denmark and individual changes in thyroid size, thyroid nodularity and serum thyroglobulin: An 11-year DanThyr follow-up investigation

Iodine is an essential mineral for the synthesis of thyroid hormones. Low iodine intake levels are associated with goitre and other iodine deficiency-related disorders that have affected billions of people worldwide. Until recently the iodine intake of many European populations was below the recommended level and iodine fortification programs are internationally recommended to ensure sufficient iodine intake. Denmark was previously iodine deficient with regional differences and a mandatory iodine fortification of household salt and salt for commercial production of bread was introduced in the year 2000. A monitoring program entitled the Danish Investigation on Iodine Intake and Thyroid Diseases (DanThyr) was initiated before any iodization of salt had begun to improve knowledge on how to evaluate iodine status in a population and to study the effects of an increase in iodine intake. The aim of this PhD thesis was to evaluate individual changes in thyroid related variables associated with iodine fortification. We chose thyroid volume, thyroid nodularity and serum thyroglobulin as indicators of impact and evaluated possible changes in an 11-year follow-up investigation performed before and after the mandatory iodine fortification of salt in two regions with different iodine intake at baseline. The PhD thesis is a part of DanThyr.