Final answer:
The symptoms described are indicative of Acute Tubular Necrosis (ATN), a condition characterized by damage to the renal tubules due to ischemia or toxic injury.
Step-by-step explanation:
The symptoms described, including the presence of epithelial cell casts and granular (muddy brown) casts in the urine, low urine specific gravity, high Na urine concentration, and low BUN/Cr ratio, are indicative of Acute Tubular Necrosis (ATN). ATN is a condition characterized by damage to the renal tubules due to ischemia or toxic injury, resulting in the presence of casts and abnormalities in urine composition.