NATURE AND TRANSPORT OF THE IODINATED SUBSTANCES OF THE BLOOD OF NORMAL SUBJECTS AND OF PATIENTS WITH THYROID DISEASE*

Abstract

FOR many years various observers, notably Plummer (1), have entertained the attractive idea that abnormal compounds of iodine might account for some of the features of Graves' disease and of the thyrotoxicosis of nodular goiter. The term “dysthyroidism” has been used to convey this idea. Thyroxine is well known to be the dominant iodinated component of the blood of the normal subject (2, 3, 4). Recently 3-5-3′- triiodothyronine has also been demonstrated in the peripheral blood of normal subjects (5). However, no other iodinated compound has been identified in the blood of man, except after heavy radiation. The iodinated organic components of the blood are closely associated with plasma protein. They are precipitated with the protein and may readily be extracted from plasma with butanol. In addition, blood contains a small amount of inorganic iodide. Gordon, Gross, O'Connor and Pitt-Rivers (6) fractionated the proteins of serum by the method of paper electrophoresis and demonstrated not only that thyroxine labeled in vivo by the administration of I¹³¹ is associated with protein possessing the mobility of alpha-globulin, but that labeled thyroxine added to serum in vitro also becomes associated with this same serum protein component. Also Larson, Deiss and Albright (7, 8) found that thyroxine is bound to a serum protein which appears in the electrophoretogram just ahead of the alpha-2 globulin (inter-alpha zone). This protein has been further characterized by Robbins et al. (9, 10,11). Schmid (12) found that the greatest concentration of protein-bound iodine was in an alpha-glycoprotein fraction.