Thyrotropin biosynthesis and carbohydrate processing has been studied under various physiologic conditions and in the presence of various inhibitors. Deoxynojirimycin, which inhibits glucosidase action and leads to accumulation of glucosylated precursors, caused inhibition of thyrotropin secretion. Thyroid hormone and thyrotropin-releasing hormone caused differential effects on thyrotropin apoprotein and carbohydrate synthesis and secretion. TSH carbohydrate structure is heterogeneous, and thyrotropin-releasing hormone caused a specific increase in synthesis and secretion of biantennary complex forms. Patients with invasive thyrotropin-secreting pituitary tumors may secrete TSH with aberrant carbohydrate structure.
