Evaluation of renal tubular damage in liver cirrhosis by urinary enzymes and beta-2-microglobulin excretions.

To assess the renal tubular damage in liver cirrhosis the fractional clearances of beta-2-microglobulin (B2m-fr.cl) and malate-dehydrogenase (MDH-fr.cl) were measured respectively in sixty-four and in forty-six out of seventy-nine patients with liver cirrhosis of different aetiology; furthermore the fractional excretions of gammaglutamyl-transpeptidase (fr-GGT) and of alpha-glucosidase (fr-AGL) were determined in fifty-three and in forty of them respectively. In all patients glomerular filtration rate (GFR) and renal plasma flow (RPF) were also measured. Twenty-five subjects were studied as a control group for the enzyme excretions, sixteen for B2m-fr.cl. B2m-fr.cl and MDH-fr.cl--indexes of tubular functions--on the average were normal and only slightly increased respectively in cirrhotics compared to controls. Nevertheless fr-GGT and fr-AGL--indexes of cytolysis of tubular cells--on the average were massively increased in cirrhosis compared to controls, particularly in those with reduced RPF and/or GFR. No clear relationship between the indexes of tubular damage studied and the indexes of liver function was found. Our results show that (1) A renal tubular anatomical damage was found by means of an increase in the release of enzyme from tubular cells in patients with liver cirrhosis, particularly in those with a significant reduction of RPF and/or GFR; even so renal reabsorption of low molecular weight proteins is generally maintained. (2) The tubular damage does not seem to be related to the degree of liver impairment.