Integrated biomarkers and renal Doppler for early acute kidney injury diagnosis in hepatitis C virus cirrhosis

Figure 6 Proposed stepped-care clinical pathway for diagnosis and triage of acute kidney injury in decompensated cirrhosis. This algorithm synthesizes key findings into a practical, resource-conscious framework for clinical implementation. Step 1: Serum neutrophil gelatinase-associated lipocalin (NGAL) measurement at initial clinical suspicion provides rapid triage, distinguishing low-risk (NGAL < 150 ng/mL) from high-risk (NGAL ≥ 150 ng/mL) acute kidney injury. Step 2: For high-risk patients, targeted bedside ultrasonography assesses renal resistive index (RRI) and volume status (inferior vena cava collapsibility, lung B-lines). An RRI ≥ 0.74 supports a diagnosis of hepatorenal syndrome and prompts consideration for intensive care unit admission and vasopressor therapy. An RRI < 0.74 suggests acute tubular necrosis or mixed injury, guiding conservative or renal-protective management. Step 3: Additional confirmatory tests (e.g., urinary microscopy, cystatin C) are reserved for cases with ambiguous initial findings. This sequential approach aims to replace delayed creatinine-based diagnosis with early, etiology-directed management, optimizing intensive care unit resource use and therapeutic decision-making. AKI: Acute kidney injury; ATN: Acute tubular necrosis; ICU: Intensive care unit; NGAL: Neutrophil gelatinase-associated lipocalin; POCUS: Point-of-care ultrasound; RRI: Renal resistive index.