Urine microscopy score (Perazella index) is a simple score that consists of measuring granular casts and renal tubular epithelial cell casts. It is used to differentiate between acute tubular necrosis and pre-renal AKI. Higher the score, more severe the AKIN staging and mortality. Urine microscopy done by Nephrologist has been found to be far superior to the one done by lab technicians.