Endemic Goiter in Greece: Metabolic Studies1

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Abstract
Iodine meta-bolism studies were performed in goitrous and nongoitrous inhabitants of the endemic areas of Central Greece. All the groups investigated showed an I2-deficiency pattern, characterized by low plasma inorganic iodine (PII) and urinary iodine excretion values, high radioiodine uptake and clearance rates, but normal values for the absolute I2 uptake and PBI. There was a tendency for the goitrous to have a higher radioiodine uptake, and in one village a lower PII level. The PBI values, although generally normal, had a mean value slightly below that of the controls from a nonendemic area, and the difference was significant for the male group. The intrathyroidal exchangeable I2 pool was reduced in the goitrous persons. The excretion of urinary I2 was more severely reduced in the females. There was no difference in the renal I- clearance between goitrous and nongoitrous persons. The butanol-insoluble I2 was higher in the goitrous than in the controls from a nonendemic area, with intermediate values in the nongoitrous inhabitants from the endemic region. The perchlorate discharge test was consistently negative. There was no evidence of decreased deiodinase activity in the goitrous, since they excreted a smaller proportion of a tracer dose of labeled monoiodotyrosina than the nongoitrous. The I2 content of the milk and the drinking water was low; relatively higher values were found in the milk of goats or sheep than in that of cows. No goitrogen could be detected, and a search for thyroid autoantibodies gave negative results. It is concluded that all the inhabitants of the endemic areas are I2 deficient, but only part of them ''evelop a goiter. There is not a single cause responsible for this difference in gland size, but possibly this is due to the interplay of many factors, such as the severity of I2 deficiency, the rates of iodine loss from the body, the relative efficiency of the I--trapping mechanism of the gland and its biosynthetic capacity.