Effect of an Ovulatory Suppressant on the Serum Protein-Bound Iodine and the Red-Cell Uptake of Radioactive Trimodothyronine

THE binding capacity of plasma proteins for thyroxine is a major determinant of the serum protein-bound-iodine level. Variations in protein binding result in alterations in this level but do not necessarily influence metabolic status. The active or "free" hormones probably remain unchanged owing to a shift in binding equilibrium. The red-cell uptake of radioactive tri-iodothyronine is a convenient indirect measure of binding capacity that has been applied as a diagnostic test of thyroid function.1 In general, increased binding of thyroid hormones is associated with decreased values for the red-cell uptake of the hormone. Pharmacologic agents such as salicylates, hydantoins and . . .