To investigate whether serum KIM-1 might allow assessment of acute kidney dysfunction, similar to urinary KIM-1 and alongside its elevation in both sepsis and critically ill patients who died in the ICU, we analysed critically ill patients who met the criteria for acute or acute-on-chronic renal injury (defined as a serum creatinine increase of at least 1.5 times or at least 0.3 mg/dL in the first 48 h, as established by the Kidney Disease: Improving Global Outcomes guidelines for acute kidney injury, KDIGO [41]). The gene discussed is HAVCR1; the disease is Sepsis.