Nitrite and nitrate levels in patients with cirrhosis of the liver: Influence of kidney function and fasting state

Background: Increased serum nitrite/nitrate (NOx) levels, the stable metabo lites of nitric oxide (NO), have been reported in patients with cirrhosis. NOx levels, however, are influenced not only by endogenous NO synthesis but also by urinary NOx excretion and dietary intake. We attempted to elucidat e factors that influence NOx levels independently of endogenous NO producti on and to determine the conditions under which NOx levels reflect endogenou s production in patients with cirrhosis and healthy controls. Methods: NOx serum concentrations and urinary NOx excretion were determined by means of the Griess reaction in relation to Child-Pugh score, kidney function, fasti ng state, and after exposure to tap water. Results: Multifactor regression analysis showed inulin clearance (P = 0.0074) and Child-Pugh score (P = 0.0 001) to be independent factors predicting NOx levels in patients with cirrh osis. NOx serum levels correlated negatively with the inulin clearance (P < 0.0001), which deteriorated with progressive loss of liver function. NOx l evels decreased by about 30% within a 24-h fasting period. After 24 h fasti ng urinary NOx excretion was not significantly increased in patients with a dvanced cirrhosis. Conclusions: NOx serum levels, taken as a surrogate for endogenous NO formation, have to be viewed with caution in patients with ci rrhosis because they often have impaired kidney function. However, in stead y-state conditions after an adequate fasting period NOx levels might be goo d prognostic markers in patients with cirrhosis since they reflect two poss ible sequelae of Liver insufficiency-namely, increased NO formation and imp aired kidney function.