Amylase in thyroid tissues from normal and various thyroid diseases. Biochemical and immunohistochemical study.

Amylase activity was measured in thyroid tissues of various thyroid diseases and was analysed electrophoretically. Normal thyroid tissues contained significant amounts of amylase (mean +/- SD; 2.71 +/- 1.15 IU/g of tissue), and their amylase isozyme was composed of a majority of salivary type isoamylase and other peculiar isoamylase. The statistical decrease of amylase activities in tissues of Graves' disease under hyperthyroidism, thyroid carcinoma, and most of thyroid adenomas were found (Graves' disease; 1.04 +/- 0.41, carcinoma; 1.49 +/- 1.10, adenoma (except five cases with high activity); 0.88 +/- 0.49 IU/g tissue). Five of 18 cases of adenoma showed strikingly higher amylase activity in their tissues. Electrophoretical patterns of amylase isoenzymes in these five adenoma tissue were different from those of normal thyroid tissues. The cellular localization of amylase in the normal thyroid tissues and the adenoma tissues was also demonstrated immunohistochemically.