Indocyanine green clearance as a test for hepatic function. Evaluation by dichromatic ear densitometry

Abstract

Clinical evaluation of liver function is facilitated by use of dichromatic ear densitometry to study clearance of indocyanine green (ICG). Densitometry provides an accurate index to arterial levels of this dye. Sequential clearance studies in the same patient with increasing doses of ICG demonstrate that a sufficiently high dose of this dye permits differentiation of patients with mild liver injury from those with normal liver. Subjects with mild liver-cell damage or hepatic excretory defects have normal clearance of 0.5 mg of ICG/kg of body weight, but impairment in the removal of 5 mg/kg. Patients with severe liver disease have reduced ICG removal rates at both low and high dose levels.