Increased High-Molecular-Weight Thyrotropin with Impaired Biologic Activity in a Euthyroid Man

CIRCULATING high-molecular-weight forms of many polypeptide hormones have been described, but there have been few reports of their occurrence as the predominant forms of glycoprotein hormones.1 2 3 4 5 6 7 8 This paper describes the presence, in a healthy young man, of a high-molecular-weight species of immunoreactive thyrotropin (TSH), which bound normally to the TSH receptor but showed decreased stimulation of the adenylate cyclase of human thyroid membranes.Case ReportDuring studies of 30 to 40 normal medical-student volunteers, a healthy 29-year-old man was discovered to have an elevated serum TSH level in a double-antibody radioimmunoassay. His history was noncontributory, and there was no family . . .