AN UNUSUAL INSTANCE OF THYROXINE-BINDING BY HUMAN SERUM GAMMA GLOBULIN*

Thyroxine comprises the major portion of the serum iodine in euthyroid and hyperthyroid humans (1–3). Gordon et al. (4) and others have demonstrated that most of the serum thyroxine is attached to an alpha globulin, and the remainder is bound to albumin. Little or no thyroxine has been found in association with the beta and gamma globulins. The present report describes the unusual occurrence of thyroxine-binding by serum gamma globulin in a patient with functioning carcinoma of the thyroid. This was a unique finding among 23 such patients in whom detailed studies of the serum iodine were performed (5).