Content and heterogeneity of distribution of iodine in human and bovine thyroid glands determined by neutron activation analyses.

While performing activation analytical investigations on the actual concentration of the long-lived radioactive 129iodine in human and bovine thyroid glands the absolute natural nonradioactive 127 iodine content was determined. In all thyroid glands an uneven distribution of 127I was found (in human thyroids from 0 to 0.75 micrograms 127I /mg, in bovine thyroids from 0 to 3.5 micrograms 127I /mg). The mean value of iodine concentration in human thyroid glands ranged from 230 micrograms/g to 490 micrograms/g. This is important because TSH independent autonomy is found at a cellular and follicular level during the development from diffuse to nodular goiter. Both processes may, however, not be related to each other. The resolution of the method used in our study is between the microscopic and the scintigraphic level with an accuracy of +/- 1%, and it shows an intermediate heterogeneity of iodine in thyroid glands.