the Occurrence of Associated Plasma Transport Ab- normalities in a Patient with an Idiopathic Increase in the Plasma Thyroxine- binding Globulin*

Since its discovery in 1952, much has been learned concerning the thyroxine (T4)-binding globulin of human plasma (TBG) [cf. Reviews (1, 2)]. Although its concentration in plasma has not been directly measured and is presum-ably very low, the capacity of TBG to bind T4 is readily measured and is normally about 20 ug per 100 ml of serum or plasma (1). Recently, several patients have been described in whom the T4-binding capacity of TBG is either greatly in-creased or decreased, apparently on a hereditary basis (3-8). Physiological studies in such pa-tients have contributed much to a formulation of the role of this protein in the peripheral metabo-lism of T4 (3, 5, 7, 8). On the other hand, little has been done to elucidate either the cause of the protein abnormality itself or the presence of asso-ciated abnormalities in other plasma transport proteins. The availability of a patient with an apparently idiopathic increase in the T4-binding capacity of TBG has made possible further studies of this disorder. Since ceruloplasmin [cf. Review (9)] and the corticosteroid-binding globulin (trans-cortin) (10-14), like TBG (15-17), normally in-crease in concentration or binding activity in re-* Submitted for publication June 29, 1964; accepte