HRS: Liver and Kidney and Heart, Oh My?

Structured Summary: "HRS: Liver and Kidney and Heart, Oh My?"

Presenter: Robert S. Brown Jr., MD, MPH | Source: Chronic Liver Disease Foundation

1. Main Clinical Topics Discussed

• Hepatorenal Syndrome (HRS): pathophysiology, evolving nomenclature, and diagnostic criteria
• Acute Kidney Injury (AKI) staging in cirrhosis
• Limitations of serum creatinine as a renal biomarker in liver disease
• Role of systemic inflammation in HRS pathogenesis
• Emerging therapies including terlipressin

2. Key Learning Points, Guidelines, and Recommendations

Pathophysiology

• HRS results from a combination of hemodynamic dysfunction (splanchnic vasodilation, reduced renal blood flow, low SVR) and systemic inflammation driven by bacterial translocation in portal hypertension
• Elevated cytokines (IL-6, TNF-α, VCAM) are observed and their magnitude correlates with AKI severity and persistence
• Prolonged renal vasoconstriction can cause tubular damage; therefore, HRS can coexist with acute tubular necrosis (ATN)
• HRS should be considered a syndrome, not a diagnosis of exclusion — coexisting renal pathologies are possible

Evolving Nomenclature

• HRS Type 1 → HRS-AKI: More severe, rapidly progressive form
• HRS Type 2 → HRS-CKD (also proposed: HRS-NAKI or HRS-AKD): Less severe, associated with refractory ascites
• AKD (Acute Kidney Disease): Intermediate category between AKI and CKD — duration >7 days but <3 months; reversibility uncertain

Diagnostic Criteria Updates (KDIGO / International Club of Ascites)

• New AKI definition: rise in serum creatinine ≥0.3 mg/dL within 48 hours or ≥1.5× baseline within 7 days
• Replaces old definition (doubling of creatinine to >2.5 mg/dL within 2 weeks with oliguria)
• Staging: Stage 1a (creatinine <1.5 mg/dL), Stage 1b (≥1.5 mg/dL), Stages 2–3 (2–3× and ≥3× baseline or need for renal replacement)
• Oliguria removed from formal criteria due to measurement challenges, but remains clinically relevant prognostically
• Presence of oliguria, low blood pressure, and low urine output is physiologically consistent with HRS

Renal Biomarkers

• Serum creatinine: Overestimates GFR in cirrhosis due to low muscle mass, poor protein intake, and high tubular secretion; affected by bilirubin interference; discriminates against women in MELD scoring
• Cystatin C: Produced by all nucleated cells; filtered freely without tubular secretion; unaffected by muscle mass, age, or bilirubin; superior GFR estimation, especially when GFR <50–60 mL/min
• Recommendation: Routine cystatin C measurement should be considered; integration into MELD scoring could improve accuracy

3. Specific Clinical Data and Study Results Cited

• Stage 1a vs. 1b outcomes (n ≈ 200 patients):

- Stage 1a (creatinine <1.5): ~90% resolution; 3-month survival 84%

- Stage 1b (creatinine ≥1.5): 3-month survival 58%; 3-month mortality 16–40%

• Survival curves demonstrate that once creatinine crosses 1.5 mg/dL (Stage 1b, 2, or 3), prognosis deteriorates markedly
• Patients with Stage 1a can double their creatinine and remain below 1.5 — yet still have meaningfully worse outcomes than those with no AKI
• Oliguria in ICU patients with renal dysfunction independently predicts poor outcome regardless of creatinine level
• GFR comparison: In healthy individuals, creatinine