how is it diagnosed?
The major criteria include liver disease with portal hypertension, kidney failure, the absence of shock, etc. The minor criteria are a low urine volume, low sodium concentration in the urine, a urine osmolality that is greater than that in the blood, the absence of red blood cells in the urine, and a serum sodium concentration of less than 130 mmol/L.
Hepatorenal syndrome
The major criteria include liver disease with portal hypertension; kidney failure; the absence of shock, infection, recent treatment with medications that affect the function of the kidney (nephrotoxins), and fluid losses; the absence of sustained improvement in kidney function despite treatment with 1.5 litres of intravenous normal saline; the absence of proteinuria (protein in the urine); and, the absence of kidney disease or obstruction of kidney outflow as seen on ultrasound.

The minor criteria are the following: a low urine volume (less than per day), low sodium concentration in the urine, a urine osmolality that is greater than that in the blood, the absence of red blood cells in the urine, and a serum sodium concentration of less than 130 mmol/L.
why does liver failure lead to kidney failure Due to "Hepatorenal Syndrome”, a life-threatening medical condition that causes rapid deterioration in kidney function in individuals with cirrhosis or fulminant liver failure. how is it caused? It usually affects individuals with cirrhosis and elevated pressures in the portal vein system. It is most common in individuals with alcoholic cirrhosis, particularly if there is concomitant alcoholic hepatitis identifiable on liver biopsies. It can also occur in individuals without cirrhosis, but with acute onset of liver failure, termed fulminant liver failure.
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Hepatorenal syndrome [SEP] Diagnosis
There can be many causes of kidney failure in individuals with cirrhosis or fulminant liver failure. Consequently, it is a challenge to distinguish hepatorenal syndrome from other entities that cause kidney failure in the setting of advanced liver disease. As a result, additional major and minor criteria have been developed to assist in the diagnosis of hepatorenal syndrome. The major criteria include liver disease with portal hypertension; kidney failure; the absence of shock, infection, recent treatment with medications that affect the function of the kidney (nephrotoxins), and fluid losses; the absence of sustained improvement in kidney function despite treatment with 1.5 litres of intravenous normal saline; the absence of proteinuria (protein in the urine); and, the absence of kidney disease or obstruction of kidney outflow as seen on ultrasound.