Hepatorenal Syndrome Types
Hepatorenal syndrome is classified into two types: Type 1 HRS (now termed HRS-AKI) characterized by rapid, progressive renal impairment with serum creatinine increasing ≥100% to >2.5 mg/dL in less than 2 weeks, and Type 2 HRS (now termed HRS-CKD) featuring stable or slowly progressive renal impairment with a more chronic course. 1
Type 1 HRS (HRS-AKI)
Rapid deterioration: Type 1 HRS demonstrates acute, progressive renal failure with serum creatinine doubling to values >2.5 mg/dL within 2 weeks or creatinine clearance falling below 20 mL/min 2
Precipitating events: This form typically occurs after a trigger event, most commonly bacterial infections (particularly spontaneous bacterial peritonitis, which precipitates HRS in approximately 30% of cases), though it can develop spontaneously 1, 3
Prognosis without treatment: Median survival is approximately 1 month (some studies report as short as 1.7-2 weeks), making this a medical emergency requiring immediate intervention 1, 4, 5
Clinical presentation: Characterized by acute kidney injury rather than chronic kidney disease, with rapid functional decline 6
Type 2 HRS (HRS-CKD)
Stable or slowly progressive: Type 2 HRS features moderate renal impairment with serum creatinine >1.5 mg/dL that remains relatively stable over time, without the rapid deterioration seen in Type 1 7, 2
Primary clinical manifestation: The dominant feature is refractory ascites that does not respond adequately to diuretic therapy 4, 6
Better prognosis: Median survival is approximately 6 months, significantly longer than Type 1 HRS 4, 5
More chronic course: This represents a chronic kidney disease pattern rather than acute kidney injury, with less urgent but still serious implications 7
Updated Nomenclature
Modern terminology shift: The International Club of Ascites has updated nomenclature to align with current nephrology standards, renaming Type 1 HRS as "HRS-AKI" (hepatorenal syndrome-acute kidney injury) and Type 2 HRS as "HRS-CKD" (hepatorenal syndrome-chronic kidney disease) 6
Rationale for change: This revision reflects the recognition that HRS is not purely "functional" but has structural components involving systemic inflammation, oxidative stress, and bile salt-related tubular damage 6
Critical Diagnostic Distinctions
AKI staging for Type 1/HRS-AKI: Stage 1 (creatinine increase ≥0.3 mg/dL up to 2-fold baseline), Stage 2 (2-3 fold increase), Stage 3 (>3-fold increase or >4 mg/dL with acute increase ≥0.3 mg/dL or initiation of renal replacement therapy) 1
Abandonment of fixed thresholds: The old criterion requiring creatinine >1.5 mg/dL has been removed because it delays diagnosis; current criteria emphasize dynamic changes rather than absolute values 1