Protein—Bound Iodine in Serum and Thyroidal Uptake of I¹³¹

Abstract

Values for protein-bound iodine (PBI) and for uptake and excretion of radioiodine may be altered by a number of drugs and diagnostic chemicals, particularly the organic iodinated compounds that are used in radiography.

In appraising thyroid function, caution is suggested in interpreting any increased PBI value or suppressed I¹³¹ uptake months after ingestion of these radiographic contrast media, although most tests are reliable after three months, with the exception of the PBI following ingestion of iophenoxic acid.