How to diagnose hepatorenal syndrome?

From the Guidelines

Diagnosing hepatorenal syndrome (HRS) requires a systematic approach based on specific diagnostic criteria, including the presence of cirrhosis with ascites, acute kidney injury, and a lack of response to volume expansion with albumin, as outlined in the most recent guidelines 1. To confirm a patient is having hepatorenal syndrome, the following steps should be taken:

• Establish the presence of cirrhosis with ascites and acute kidney injury, defined as a serum creatinine increase of at least 0.3 mg/dL within 48 hours or a 50% increase from baseline.
• Rule out other causes of kidney injury by ensuring the patient has not responded to volume expansion with albumin (typically 1 g/kg daily up to 100 g for 48 hours), has no recent use of nephrotoxic drugs, and shows no evidence of shock, parenchymal kidney disease, or urinary tract obstruction.
• Laboratory findings typically show low urine sodium (<20 mEq/L), high urine osmolality compared to plasma, and minimal proteinuria (<500 mg/day), as noted in studies 1.
• Urinary sediment should be normal or with minimal abnormalities.
• HRS is classified into two types: type 1 presents as rapidly progressive renal failure with creatinine doubling to >2.5 mg/dL within two weeks, while type 2 shows moderate, stable renal impairment, as described in 1. The pathophysiology involves splanchnic vasodilation leading to reduced effective arterial blood volume, intense renal vasoconstriction, and decreased glomerular filtration rate despite normal kidney structure, as explained in 1. Prompt diagnosis is crucial as HRS carries high mortality, especially type 1, and early treatment with vasoconstrictors (terlipressin, norepinephrine, or midodrine plus octreotide) combined with albumin can improve outcomes, as recommended in 1.

From the Research

Diagnosis of Hepatorenal Syndrome

To confirm a patient is having hepatorenal syndrome, the following steps can be taken:

• Diagnosis is based on the reduction in renal blood flow and glomerular filtration rate in patients with cirrhosis 2
• Two forms of hepatorenal syndrome are recognized: HRS-AKI (acute kidney injury) and HRS-CKD (chronic kidney disease) 3, 4, 2
• HRS-AKI is characterized by a severe impairment of kidney function owing to vasoconstriction of the renal arteries in the absence of substantial abnormalities in kidney histology 4
• Differential diagnosis with other causes of AKI is crucial because HRS-AKI requires a specific treatment 3, 4

Diagnostic Criteria

The diagnostic criteria for hepatorenal syndrome include:

• Reduction in kidney function in patients with cirrhosis 2
• Absence of evidence of intrinsic kidney disease, such as hematuria, proteinuria, or abnormal kidney ultrasonography 2
• No other apparent cause of kidney injury, such as shock or nephrotoxic agents 5
• Response to volume expansion with albumin and vasoconstrictor drugs can help confirm the diagnosis 5, 4

Diagnostic Challenges

Diagnosing hepatorenal syndrome can be challenging due to:

• Lack of specific diagnostic tools 4
• Difficulty in differentiating HRS-AKI from other forms of AKI, particularly acute tubular necrosis 3, 4
• Need for careful evaluation of patients with cirrhosis and kidney dysfunction to determine the underlying cause of kidney injury 5, 2