Separation of hormonal and exogenous iodine in serum by means of a cation exchange resin

The influence of iodine-containing compounds on the determination of iodoamino acids (IAA) and hormonal iodine (HI) in serum with a cation exchange resin has been studied. The IAA values were elevated by most of the compounds, though to a lesser degree than the protein-bound iodine. Of 15 chemically different iodinated radiopaques, only three caused false elevation of the HI, for periods varying from 2 to 14 days after the administration of the drug. Of a number of other iodine-containing compounds, only iodochlorhydroxyquin appeared to give variable results during its administration, all others being eliminated from the HI.