Hepatorenales Syndrom

Mechanisms in fluid retention - towards a mutual concept

Fluid retention is a common and challenging condition in daily clinical practice. The normal fluid homoeostasis in the human body is based on accurately counter-balanced physiological mechanisms. When compromised fluid retention occurs and is seen in pathophysiologically different conditions such as liver cirrhosis, heart and kidney failure, and in preeclampsia. These conditions may share pathophysiological mechanisms such as functional arterial underfilling, which seems to be a mutual element in cirrhosis, cardiac failure, cardiorenal and hepatorenal syndromes, and in pregnancy. However, there are also distinct differences and it is still unclear whether kidney dysfunction or arterial underfilling is the initiating factor of fluid retention or if they happen simultaneously. This review focuses on similarities and differences in water retaining conditions and points to areas where important knowledge is still needed.

Fractional excretion of sodium in hepatorenal syndrome: Clinical and pathological correlation

AIM

To determine the accuracy of fractional excretion of sodium (FeNa) in the diagnosis of hepatorenal syndrome (HRS).

METHODS

Eighty-eight liver transplantation candidates with renal dysfunction and/or proteinuria were included in the study sample. The baseline characteristics of the patients were obtained. All the 88 patients underwent iothalamate glomerular filtration rate testing, 24-h urine collection for urinary sodium and protein excretions, random urine for sodium and creatinine testing, and percutaneous kidney biopsy. FeNa was calculated using the equation [(urine sodium × serum creatinine)/(serum sodium × urine creatinine)] × 100%. Diuretic use was recorded among the participants. Patients on renal replacement therapy were not included in the original sample.

RESULTS

Seventy-seven (87%) of the 88 patients had FeNa < 1%. FeNa < 1% was present in 10/10, 10/12, 11/13, 12/15 and 34/38 in patients with HRS, acute tubular necrosis, membranoproliferative glomerulonephritis, minimal histological findings (≤ 30%) and advanced (≥ 30%-40%) interstitial fibrosis and/or glomerulosclerosis, respectively (P = 0.4). FeNa < 1% was 100% sensitive and 14% specific in diagnosing HRS. Receiver operating characteristic curve confirmed the poor accuracy of FeNa < 1% in diagnosing HRS (area under the curve = 0.58, P = 0.47). Calculated positive predictive value and negative predictive value for FeNa < 1% in HRS diagnosis were 46% and 100%, respectively. When used as a continuous variable, FeNa did not correlate with kidney biopsy findings (P = 0.41).

CONCLUSION

FeNa < 1% was common in cirrhotic patients with renal dysfunction and it did not differentiate between HRS and other causes of renal pathologies. HRS diagnosis should be avoided in patients with FeNa > 1%.

[Anesthesia with liver failure]

Liver failure can be categorized into acute liver failure, chronic liver failure and acute decompensation of chronic liver failure, the so-called acute-on-chronic liver failure, the incidence of which has increased over the last few years. Liver failure leads to a variety of pathophysiological changes where the extent is dependent on the nature and duration of the liver disease. This includes restriction of synthesis and metabolism, such as coagulation defects. Especially chronic liver failure is associated with malfunction of extrahepatic organs, such as the cardiovascular system, the respiratory system and the kidneys. In addition to these pathophysiological alterations the Child-Turcotte-Pugh classification (CTP) and the model of end stage liver disease (MELD) are used for perioperative risk stratification.