Understanding the Trajectory of Kidney Dysfunction in Cirrhosis—the AKI-CKD Spectrum

Overview

This lecture by Prof. Rakhi Maiwall explores the spectrum of kidney dysfunction in cirrhosis — spanning acute kidney injury (AKI), acute kidney disease (AKD), and chronic kidney disease (CKD) — with emphasis on pathophysiology, diagnosis, phenotyping, and management implications in decompensated liver disease.

Key Clinical Topics

• Definitions and temporal boundaries of AKI, AKD, and CKD in cirrhosis
• Pathophysiologic mechanisms driving progression from AKI to CKD
• Concept of renal functional reserve and its clinical relevance
• Role of cystatin C as a biomarker in cirrhosis-related kidney dysfunction
• De novo CKD development in cirrhotic patients
• Functional versus structural phenotyping of kidney dysfunction
• Maladaptive renal repair and fibrosis progression
• Kidney outcomes in the context of liver transplantation

Key Learning Points

• AKI definition in cirrhosis: rise in serum creatinine by ≥0.3 mg/dL within 48 hours or by ≥50% within 7 days of baseline
• Acute kidney disease (AKD): kidney dysfunction of uncertain or prolonged duration; GFR reduction of >35% from baseline, or kidney insult persisting beyond the AKI window but fewer than 90 days
• Chronic kidney disease (CKD): GFR reduction sustained beyond 90 days; can develop de novo or on a background of pre-existing kidney disease
• Overlapping phenotypes: patients may present with AKI-on-AKD, AKI-on-CKD, or concurrent AKD and CKD, requiring careful phenotypic assessment
• Serum creatinine limitations: creatinine is an inaccurate marker of kidney function in cirrhosis due to reduced muscle mass; estimated GFR (eGFR) is preferred in clinical practice
• Renal functional reserve: the increment in GFR following physiologic challenge (e.g., protein or amino acid loading); diminishes with each AKI episode even when creatinine and eGFR appear to have normalised
• Maladaptive renal repair: driven by severe tubular epithelial injury, neutrophil and macrophage infiltration, ferroptosis (iron-mediated lipid peroxidation), mitochondrial dysfunction, and cell cycle arrest; leads to pericyte proliferation, collagen deposition, myofibroblast activation, and irreversible fibrosis
• MAFLD and IgA nephropathy: comorbid conditions such as metabolic dysfunction-associated fatty liver disease, diabetes, and hypertension confer independent risk for CKD independent of AKI episodes
• Baseline kidney assessment: in all patients with decompensated cirrhosis, evaluate baseline serum creatinine, eGFR, renal imaging, urine microscopy, and prior AKI history before attributing any acute deterioration

Clinical Data & Study Results

• ILBS prospective cohort (2016): cystatin C outperformed serum creatinine in predicting future AKI episodes; patients with prior AKI demonstrated a compounding predisposition to subsequent AKI episodes
• MELD-cystatin C score: developed and validated as a superior predictor of mortality compared to standard MELD in cirrhotic patients with kidney dysfunction
• De novo CKD cohort (n = 818): in a large prospective outpatient cohort of stable decompensated cirrhotic patients, 1 in 3 developed CKD on follow-up; key predictors included prior AKI within the preceding 3 months, baseline cystatin C >2, and severity of liver disease
• AKI type and CKD risk: acute tubular necrosis (ATN), compared with hepatorenal syndrome (HRS-AKI), was associated with higher rates of progressive renal dysfunction

Practical Takeaways

• Assess eGFR — not serum creatinine alone — at every outpatient visit for patients with decompensated cirrhosis to detect subclinical kidney dysfunction early
• Obtain a thorough history of **prior