Analysis of the sodium iodide symporter expression in histological slides from a nodular goiter

The aim of the study was analysis at both the level and the cell site of the sodium/iodide symporter (NIS) in histological slides from hot, warm, and cold nodules and extranodular parenchyma according to scintigraphy.

The study population consisted of 97 people who underwent surgery for a toxic nodular goiter (26 patients) or a non-toxic nodular goiter (71 patients). Immunohistochemical study was performed with 198 histological slides from hot, warm, and cold nodules (study slides) and the extranodular parenchyma (control slides). The level of NIS expression was estimated objectively using the computerized image analysis system, Quantimet 600S (Leica, Cambridge, UK).

We found significantly higher NIS expression in hot nodules than in cold nodules and in warm nodules than in cold ones. We found significantly higher NIS expression in hot and warm nodules than in the surrounding parenchyma. The level of NIS expression did not differ significantly between cold nodules and the collateral tissues.

Our data indicate that NIS protein participates in the development of hyperthyroidism in the course of a nodular goiter. We confirm that the functional state of a nodular goiter is determined by NIS expression in nodules, not in collateral parenchyma. The low metabolism of cold nodules does not simply result from decreased level of NIS protein or its defective targeting to the cell membrane. The observation of NIS in the cell cytoplasm of hot nodules seems to indicate that the intracellular localization of NIS does not determine loss of its activity.