Is There Evidence for Substances In Serum Which Can Affect T4 Binding To Proteins?
In patients with advanced renal disease who have not been recently dialyzed, there is possibly the accumulation of substances, as noted above, which can alter binding of T4 (29). These materials could be dialyzed out promptly during assays of free hormone, and therefore cause the assay to record an apparently low free T4. Evidence for dialyzable and non-dialyzable inhibitors of T4 binding has been presented by Chopra (36). The material in serum was thought possibly to be fatty acids. In contrast, Mendel and colleagues (37) found no evidence for an inhibitor of thyroxine binding to serum proteins in a study of a series of 111 patients from acute care wards. It should be noted that almost all subjects had T4 values within the normal range. Only 3 had values below 4 g/dl. Thus the patients may not have been optimal for studying evidence of a binding inhibitor. As reviewed by Mendel et al (37), one of the main concerns regarding an inhibitor of binding is the potential effect of elevated f
