phentetiothalein

phen·tet·io·tha·lein .fen-.tet-ī-ō-'thal-ē-ən, -'thāl- n a substance or its disodium salt C₂₀H₈I₄Na₂O₄ isomeric with iodophthalein used esp. formerly as a radiopaque medium in cholecystography and in tests of liver function called also phenoltetraiodophthalein