The discrepancy between plasma clearance tests of indocyanine green (ICG) and sulfobromophthalein (BSP): --report of cases and a study of ICG-binding pattern of serum proteins.

Two cases of Gilbert's syndrome and three cases of other diseases showed abnormally low plasma indocyanine green (ICG) clearance as contrated with normal or nearly normal plasma sulfobromphthalein (BSP) clearance. To evaluate the role of serum proteins in pathogenesis of these cases, ICG-binding patterns of serum proteins of the patients were compared with that of normal persons by the method of Sephadex G200 column chromatography. No qualitative differences in binding patterns were observed between serum proteins of the patients and normal persons. From these results, serum proteins were thought to be minor determinants of the hepatic ICG uptake mechanism. Because of normal or nearly normal plasma BSP clearance in these patients, the contents of hepatic organic anion-binding proteins, Y and Z, were thought to be sufficient. Possible qualitative abnormalities of the Y and/or Z proteins were also discussed.