URINARY VARIABLES IN PRE-RENAL AND ACUTE TUBULAR NECROSIS PRE-RENAL ACUTE TUBULAR NECROSIS Osmolality >500 <500 >1.020 ∼1.010 Specific gravity Sodium FENa <20 >40 <1 >2 NEW BIOMARKERS: KIM-1; NGAL; IL-18; Fetuin A