FGF21 and metabolic dysfunction-associated steatotic liver disease: Search keywords: MASLD/Non-alcoholic fatty liver disease (NAFLD); CKD (albuminuria, eGFR); renal fat; lipotoxicity; lipidomics, hepatokines, fetuin-A, Fibroblast Growth Factor 21 (FGF21), Kidney Injury Molecule-1 (KIM-1); Neutrophil Gelatinase-Associated Lipocalin (NGAL); ultrasound; controlled attenuation parameter (CAP), MRI.