Systemic nitric oxide production and renal function in nonazotemic human cirrhosis: a reappraisal

Effect of intravenous albumin on endotoxin removal, cytokines, and nitric oxide production in patients with cirrhosis and spontaneous bacterial peritonitis

OBJECTIVE

In patients with cirrhosis and spontaneous bacterial peritonitis (SBP), the use of intravenous albumin has been shown to prevent deterioration of renal function and to decrease the mortality rate, but the mechanisms remain unclear. The purpose of this study was to characterize the mechanisms of action of albumin with the focus on endotoxin and cytokines.

MATERIAL AND METHODS

Thirty patients with SBP were divided into two groups. Group 1 received antibiotics and albumin infusion (20% 50 cc every day for 3 days) and Group 2 received antibiotic treatment only. Twenty-four cirrhotic patients with sterile ascites were enrolled in Group 3 and received albumin infusion (20% 50 cc every day for 3 days). Plasma and ascitic fluid concentrations of endotoxin, nitric oxide products (NOx), tumor necrosis factor (TNF)-alpha, and interleukin (IL)-6 were analyzed before and after treatments, respectively.

RESULTS

Combination therapy of albumin and antibiotics can significantly (p<0.01) reduce plasma levels of TNF-alpha and IL-6, and ascitic fluid levels of endotoxin, TNF-alpha and IL-6 in cirrhotic patients with SBP. Without the addition of albumin to an antibiotic regimen, the plasma and ascitic fluid levels of NOx increased significantly in patients with SBP (p=0.005 and p=0.004, respectively).

CONCLUSIONS

The results confirm that the beneficial effects of albumin are related to the reduction of the levels of TNF-alpha and NOx in both plasma and ascitic fluid. The infusion of albumin continuously for 3 days in addition to antibiotic treatment at the time of SBP detection is recommended as an effective therapy for patients with cirrhosis and SBP.

Evidence of a dynamic aldosterone-independent distal tubular control of renal sodium excretion in compensated liver cirrhosis

BACKGROUND AND AIM

In preascitic cirrhosis increased sodium retention occurs in kidney distal tubule in spite of normal aldosterone plasma levels. No clearance technique can dissect the respective contribution to sodium retention exerted by Henle's loop, distal convoluted tubule and collecting duct, so we evaluated proximal and distal tubular sodium handling in preascites during two manoeuvres that temporarily increase aldosterone secretion.

METHODS

Ten patients with compensated cirrhosis and nine controls were studied in recumbency, during standing and after dopamine receptor blockade with metoclopramide through: 4 h renal clearances of sodium, potassium, lithium and creatinine; plasma levels of active renin and aldosterone.

RESULTS

Whilst comparable in recumbency, aldosterone levels significantly rose during standing and after metoclopramide in both groups. In patients, dopaminergic blockade caused a fall of distal sodium delivery (P < 0.01) but urinary sodium excretion was unchanged because the reabsorbed fraction of distal sodium delivery also fell (P < 0.03). Cirrhotic patients showed the same findings in the passage from recumbency to standing.

CONCLUSIONS

In preascitic cirrhosis, the distal tubular segments of the nephron are able to cope with decreases in tubular flow by reducing reabsorption at an aldosterone-independent site (possibly the loop of Henle).

Nitric oxide and renal function in cirrhotic patients with ascites: from physiopathology to practice

Patients with cirrhosis and ascites show systemic and splanchnic arterial vasodilation, which causes a reduction in effective arterial blood volume and the activation of hormonal anti-natriuretic systems. Renal impairment is the most important predictor of hospital mortality in cirrhotic patients with SBP. In patients with SBP, the inflammatory response to the infection (TNF-alpha, IL-6) may be an important mechanism of renal dysfunction. Ascitic-fluid NO metabolites are related independently to the development of renal impairment. Treatment of SBP with intravenous albumin in addition to cefotaxime prevents renal impairment and reduces mortality in comparison with treatment with cefotaxime alone. As soon as ascites develops, liver transplantation should be considered in eligible patients, especially when local mean waiting times exceed life expectancy. Nitric oxide (NO), tumour necrosis factor alpha (TNF-alpha) and interleukin-6 (IL-6) have been implicated in the pathogenesis of circulatory alterations observed in cirrhotic patients with ascites. Kidney failure is one of the main factors associated with mortality in patients with end-stage liver disease developing complications, particularly severe infections and variceal haemorrhage. Renal impairment occurs in patients with the highest concentration of cytokines in plasma and ascitic fluid and is associated with marked activation of the renin-angiotensin system. In patients with spontaneous bacterial peritonitis (SBP), serum and ascitic fluid levels of NO metabolites (nitrites and nitrates) were higher than those of patients with sterile ascites, and renal impairment is considered to be caused by a decrease in effective arterial blood volume as a result of the infection. The administration of albumin prevents deterioration of renal function and reduces mortality in these patients. However, SBP and renal dysfunction are late complications in the course of liver cirrhosis. As soon as ascites develops, liver transplantation should be considered in eligible patients, especially when local mean waiting times exceed life expectancy. A better knowledge of metabolic disorders associated with the early stage of cirrhosis is essential for the development of optimal therapeutic strategies for the prophylaxis and treatment of portal hypertension and its complications.