Intrathyroidal iodine heterogeneity of iodocompounds and kinetic compartmentalization.

In the normal thyroid, but not necessarily in the goitrous gland, the bulk of iodine is bound to thyroglobulin. Even in the normal thyroid-and much more so in goiters-iodine is contained in many different compartments with widely differing kinetics, biochemical composition, localization, and physiologic significance. Any change of thyroid function profoundly affects intrathyroidal iodine kinetics and produces a redistribution of stored iodine. This must be taken into account whenever the impact of a global change in intrathyroidal iodine stores on thyroid function and growth is studied in vivo.