Final answer:
The patient's symptoms and urinalysis results suggest intrarenal disease, likely acute tubular necrosis, which is a common type of intrarenal acute kidney injury that can be caused by several factors such as ischemia, nephrotoxins, or sepsis. The correct option is c. intrarenal disease, probably acute tubular necrosis.
Step-by-step explanation:
The student has presented a scenario where a patient is showing signs of acute renal failure (ARF), such as malaise, fatigue, decreased urinary output, and a urinalysis indicating muddy brown granular casts and hematuria. Based on these symptoms, especially the presence of granular casts which are a classic sign of acute tubular necrosis (ATN), it is likely that the nurse would determine the condition to be intrarenal disease, most likely acute tubular necrosis.
ATN is a form of intrarenal acute kidney injury that usually results from ischemia, nephrotoxins, or sepsis, and involves damage to the renal tubular cells, leading to their death and sloughing into the tubules, creating the characteristic muddy brown casts. This is distinguished from prerenal causes which are due to factors like hypovolemia affecting blood supply, and postrenal causes which are typically due to obstructions in the urinary tract like kidney stones or prostate issues.
For the definitive diagnosis, serum creatinine needs to be measured and compared to previous levels if available, and if the cause isn't immediately clear, a renal ultrasound is an important next step to rule out urinary tract obstruction. The correct option is c. intrarenal disease, probably acute tubular necrosis.