MASLD: Lipotoxicity and Imaging Parallels from Liver Steatosis to Kidney Injury

Metabolic dysfunction-associated steatotic liver disease (MASLD) is recognized as a systemic condition that is associated with an increased prevalence of chronic kidney disease (CKD), independent of classical risk factors. This review explores MASLD and metabolic kidney dysfunction, emphasizing lipotoxicity, emerging biomarkers, and liver-kidney fat imaging techniques. Renal fat is discussed as an ectopic lipid depot that may contribute to kidney vulnerability in the same cardiometabolic milieu as MASLD. In this context, lipotoxicity, a phenomenon intensively studied in MASLD, can affect multiple nephron segments, promoting fibrosis and, ultimately, CKD. Hepatokines may support the concept of a liver-kidney metabolic axis, but human data remain limited. Tubular biomarkers show promise for detecting early renal injury, but lack validation in large populations. Hepatic steatosis is quantified through multiple validated imaging techniques such as ultrasound, elastography, and magnetic resonance imaging (MRI). In contrast, renal fat imaging studies are limited and heterogeneous, and still lack standardization. In MASLD, an integrated hepatorenal assessment is warranted to capture the full burden of the disease.