URINARY SODIUM-BALANCE IN PATIENTS WITH CIRRHOSIS - RELATIONSHIP TO QUANTITATIVE PARAMETERS OF LIVER-FUNCTION

The relationship between the impairment in hepatic and renal function in cirrhosis has not been well established. This study investigated ur inary sodium excretion in comparison with quantitative parameters of l iver function in 75 patients with various degrees of cirrhosis kept on a constant salt diet of 120 mmol/d for 5 days before the start of the study, The aminopyrine breath test (ABT), indocyanine green (ICG) eli mination, galactose elimination capacity (GEC), and hepatic sorbitol e limination (HSE) served as quantitative parameters of liver function, Results for the quantitative tests were compared with those for the Ch ild-Pugh score. Urinary sodium excretion showed a significant nonlinea r relationship to ABT (r = .70; P < .0001). Less-significant correlati ons were observed for ICG (r = .60), the Child-Pugh score (r = -.57), GEC (r = .44), and HSE (r = .34), Because a number of significant corr elations were observed between the different liver function tests, mul tivariate analysis was used to further elucidate the relationship betw een hepatic function and sodium excretion, Only one independent predic tor of urinary sodium excretion could be identified, and that was the ABT (P < .02). More than half of the nonascitic patients showed a urin ary sodium excretion of less than 80% of dietary sodium intake, indica ting impaired renal sodium handling in pre-ascitic cirrhosis. Based on the 95% confidence interval (CI) for ABT of nonascitic patients with normal (mean ABT 0.56% dose X kg/mmol CO2; 95% CI: 0.44 to 0.69) and r educed urinary sodium excretion (mean ABT 0.26% dose X kg/mmol CO2; 95 % CI: 0.18 to 0.35), a threshold level of ABT of about 0.4 (% dose X k g/mmol CO2) for conservation of normal urinary sodium excretion in cir rhosis can be defined. This ABT value reflects an approximate 50% redu ction in function compared with the mean of cirrhotic patients with no rmal liver and kidney function (0.81% dose x kg/mmol CO2). The presenc e of ascites was also associated with a reduction in ABT to below 0.4 (% dose X kg/mmol CO2), while, for all other parameters, either the cu t-off point was close to the lower limit of normal or no cut-off level could be detected. In conclusion, the results of the present study pr ovide further evidence that the impairment in urinary sodium excretion in cirrhosis is related to hepatic function, The data suggest a nonli near relationship. Because AB-T has been shown to reflect functional h epatocellular mass, the occurrence of sodium retention and ascites app ears to be related to a threshold of an approximate 50% reduction in f unctional liver cell mass.