Estimation of the functional reserve of human liver

Functional hepatic reserve was determined in 32 patients with known liver or biliary tract disease employing kinetic analysis of hepatic removal of indocyanine green (ICG). The initial removal rates of incremental doses of ICG (0.5, 1.0 and 5.0 mg/kg body weight) were plotted as a reciprocal against the inverse of dose (Lineweaver-Burk plot) to provide a means of determining maximal removal rate from submaximal doses (Rmax). This function equalled 3.40 mg/kg/min in ten patients with normal livers, but was only .24 mg/kg/min in eight patients with alcoholic cirrhosis. Portasystemic shunting did not further influence Rmax. Infiltrative liver disease had only a mild depressive effect on this function. The results show that hepatic function can be precisely quantitated by classical enzyme kinetics (Michaelis-Menten). If Rmax is an estimate of protein receptor mass for organic anions, then the technique may allow an indirect means for quantitating hepatocytes even in the presence of changes in blood flow or hepatic function. The profound depression in R(max) observed in patients with alcoholic cirrhosis is consistent with the progressive loss in hepatic mass associated with this disease.