Splanchnic galactose uptake in patients with cirrhosis during continuous infusion

The galactose elimination capacity (GEC) is considered a test of functional liver cell mass. The main uncertainties of the method are the effects of extrahepatic elimination and of uneven distribution in the body on the calculated maximal elimination rate of galactose. This has been evaluated by hepatic and renal venous catheterization during continuous infusion of galactose at two arterial concentration levels (mean 6.0 and 8.7 mmol l-1) in 10 patients with reduced liver function. Hepatic and renal blood flow were measured by constant infusions of Indocyanine Green and 131I Hippuran. Hepatic galactose elimination rate was identical (mean 1.36 and 1.32 mmol min-1, P greater than 0.4) at the two arterial concentration levels studied, indicating that hepatic galactose elimination rate was maximal (Vmax). The total body galactose elimination rate, calculated as amount infused during steady state, was 1.4 times greater than the hepatic elimination rate, calculated as arterio-hepatic venous concentration difference times hepatic blood flow. Within the experimental error, the extrahepatic (i.e. total minus hepatic) galactose elimination could be accounted for by renal elimination. The steady state studies show that the galactose elimination capacity, estimated from single injection, overestimates the hepatic Vmax by about 25%. The reason for this is probably mainly distribution phenomena and insufficient correction for urinary loss, but extrahepatic metabolism of galactose cannot be excluded.