History of endemic goiter in Croatia: from severe iodine deficiency to iodine sufficiency

At the time after the Second World War, endemic goiter was present in most parts of Croatia with a prevalence of more than 50% and presence of cretinism. In the village of Rude near Zagreb, goiter was detected in 85% of school children with 2.3% of cretins in the village population. In 1953 the first regulation on obligatory salt iodination, requiring 10 mg of potassium iodide (KI) per kg of salt was established in former Yugoslavia. A three-fold reduction of goiter prevalence, together with disappearance of cretinism was recorded ten years later In 1992, the National Committee for Eradication of Goiter was founded. The survey performed during 1991-1993 exhibited prevalence of goiter among school children between 8% and 35% and urinary iodine excretion under 10 microg/dL in most of the children from continental parts of the country. The new obligatory regulation, requiring 25 mg of KI/kg of salt, was proposed by the National Comittee and finally established in 1996. In 2002 thyroid volumes and medians of urinary iodine excretion were normal according to the ICCIDD criteria. Overall median of urinary iodine excretion for schoolchildren in Croatia was 14 ug/dL. Croatia crossed a path from severe iodine deficiency detected in the 1950's to the period of mild to moderate iodine deficiency during the 1990's, and finally, nowadays, iodine sufficiency has been achieved.     

Metal-binding functions and antioxidant properties in human thyroid gland under iodine deficient nodular colloidal goiter

Copper and zinc levels in the tissue of thyroid gland (TG) and their metal-binding proteins metallothioneins (MT) as well as state of the antioxidant system in persons that had no thyroid disease and patients with endemic iodine deficiency nodular colloidal goiter has been investigated. In the patients with thyroid disease, oxidative damage was indicated despite elevated levels of MT-SH and glutathione, and elevated copper and decreased zinc concentration in TG tissue. MTs partly bound the excess of copper but its concentration in the unbound to MT form was two-fold compared to the control value.     

Physiological basis of goiter transformation of the thyroid gland and the pathogenesis of euthyroid goiter

Endemic goiter disease develops as a result of iodine insufficiency in the environment, that induces advancing reproduction of thyrocytes realized by endomitosis. Eventually goiter-transformed gland ceases responding to the lack of iodine in the environment, that is due to the destruction of thyrocyte ++thyroreceptors. It should be taken into account that goiter disease depends upon the female sexual hormones.     

An autosomal dominant form of adolescent multinodular goiter.

Eighteen members of an extended pedigree have been found to have a form of euthyroid adolescent multinodular goiter. Histological examination showed multiple adenomata with areas of epithelial hyperplasia, hemorrhage, and calcification. In two subjects there were focal areas of epithelial hyperplasia reminiscent of low-grade papillary carcinoma, but capsular and vascular invasion was not found. The pattern of inheritance appeared to be autosomal dominant, with diminished penetrance in males. Although the patients were euthyroid, the likely basis for this disorder is an abnormality in thyroglobulin structure and function.     

The pathology of the nodular goiter

Pathologic studies of thyroid nodules indicate that a definite percentage of nodular goiters are malignant, and that an even higher percentage are true neoplasms. Malignant tumors may arise from adenomas, involutionary nodules or possibly from nodules of the unclassified type. Some carcinomas of the thyroid gland are undoubtedly malignant processes from the start. Because of the high incidence of neoplasms, benign and malignant, in a group of single nodules of the thyroid gland, the presence of such nodules should warrant radical resections of the involved lobe and adjacent isthmus. The high incidence of epithelial growth activity in nodular involutionary goiters may revise the accepted practice of removing non-toxic nodular goiters only when clinical evidence of growth or local pressure is present.