Definition: A condition characterized by the decline of renal function occurring over hours or few days with/without reduced urine output in a variable clinical context.

Acute tubular necrosis. A renal lesion characterized by: degenerative/regenerative changes of the renal tubular epithelium; detachment of tubular cells from the tubular basement membrane; granular and epithelial (= containing renal tubular cells) casts within the tubular lumens.

In this condition, the urinary sediment contains a variable number of renal tubular epithelial cells, epithelial casts, and granular casts. The higher the number of these elements, the more likely and severe the tubular damage.