Indirect methods of assessing thyroid function. Protein-bound iodine and thyroxine by column chromatography, a 1976 CAP survey.

An assessment of the infrequently performed protein-bound iodine determinations (PBI) and thyroxine (T4) determinations by column chromatography is presented after analysis of data contributed by participants in the 1976 College of American Pathologists Chemistry Survey Programs. The two technics yield comparable mean concentrations, but there is considerable interlaboratory variance within method groups, especially among laboratories performing column chromatographic T4 iodine assays.