Effect of cow's milk from the goitre endemia district of Finland on thyroid function.

Abstract

ABSTRACT In order to elucidate the effect of a goitrogenic factor contained in milk collected in the goitre area of Finland, a series of rats was fed with milk from such a district and compared with a fully similar series fed with milk from a non-goitre area. After 1, 3, 5 and 11 weeks and 1 year the body weight, thyroid weight, thyroidal 131I uptake and serum cholesterol level of the animals in both series were determined. It was demonstrated that the thyroid of rats receiving milk from the goitre area increased much more rapidly in weight, beginning with the first week, than that of animals in the control series, the difference being statistically highly significant throughout the experiment. After the course of one year the difference was as much as twofold. The 131I uptake per weight unit of thyroid was decreased during 5 to 11 weeks in the rats receiving milk from the goitre area. The total thyroidal 131I uptake, however, showed an increasing tendency towards the end of the experiment in rats fed with milk from the goitre area, but only after one year the difference was statistically significant. In the body weight and serum cholesterol levels there were no detectable differences between the two series. This study indicates that the milk collected in a goitre area contained a goitrogen, probably of thiouracil- or thio-oxazolidone-type, the effect of which could not be eliminated by iodine ingestion in excess. The possibly decisive role of this factor in the pathogenesis of the goitre endemia in Finland is briefly discussed. Different pasturing habits of cattle in goitre and non-goitre districts may explain the occurrence of a goitrogenic factor in the milk in certain parts of the country.