EUROPEAN THYROID ASSOCIATION HENNING PRIZE LECTURE, Goteborg, 10 September 2002 Primary congenital hypothyroidism: defects in iodine pathways

The thyroid gland is the only source of thyroid hormone production. Thyroid hormone is essential for growth and development, and is of special importance for the development of the central nervous system. It was for that reason that neonatal screening on congenital hypothyroidism was introduced and is now performed in many countries. Defects in thyroid hormone production are caused by sev-eral disorders in hormone synthesis and in the development of the thyroid gland (primary hypothy-roidism) or of the pituitary gland and hypothalamus (central hypothyroidism). This paper describes defects in the synthesis of thyroid hormone caused by disorders in the synthesis or iodination of thyroglobulin, leakage of iodinated proteins by a stimulated thyroid gland and the presence of abnormal iodoproteins, mainly iodinated albumin, in the thyroid gland and blood circula-tion. Circulating thyroglobulin and abnormal iodoproteins, as well as the breakdown products of these iodoproteins excreted in urine, are used for etiological diagnosis and classification. Moreover, our finding of an enzyme that catalyses the dehalogenation of iodotyrosines, which is important for iodine recycling and required for economical use of iodine, is also referred to. European Journal of Endocrinology 149 247–25