Quantitative Studies on the in Vivo Absorption of Iodine by Dogs’ Thyroid Glands

It is common knowledge that .iodine is taken up by the thyroid very rapidly when administered in any form and by any method. It is also known that the amounts taken up from a given intake vary with the size of the gland and the existing degree of hyperplasia. These are statements of fact to the best of our knowledge, but they are also vague generalizations and on that account neither satisfying nor convincing. It is for these reasons that criticisms and doubts have been expressed, and it is for the purpose of supplying definite figures that the following experiments, though somewhat old, are reported. The plan of the experiments was as follows: With the usual aseptic precautions one lobe was removed, cleaned, and weighed. A weighed port,ion was kept for histological examination, and the remainder dried at 70” for the determination of its iodine content. 50 mg. of either potassium iodide or sodium iodide were given in 5 mg. doses by mouth for the following ten days; then, after an interval varying from five to eight days, the remaining lobe was removed, cleaned, drained of blood, and weighed. A weighed portion was kept for histological examination and the remainder dried for iodine determination. Six experiments have the above mentioned constant features, and the principal data are tabulated on the following page. As regards weight of the animals and size of the thyroid lobes, there is fairly wide range between minimum and maximum. So also as regards sex and age the data are sufficient’ to indicate that no important change is related to t,hese factors. The histoiogical condition of the control lobes includes examples of our t.hree arbitrary divisions of the several degrees of hyper-