Acute tubular necrosis

Acute tubular necrosis is a common type of acute kidney injury, particularly in hospitalized patients.

Pathology

Acute tubular necrosis is characterized by renal tubular cell damage and death and is usually caused by ischemic or nephrotoxic insults. Deposition of cellular debris within the tubules results in oliguria. Urine microscopy for renal tubular epithelial cells and granular casts may be helpful to confirm a diagnosis.

Etiology

• hypovolemia/ischemia
  • dehydration
  • blood loss / renal hypoperfusion
  • septic shock
• drugs
  • amphotericin B
  • iodinated contrast media
  • cisplatin
  • sulfa drugs
  • antiviral (acyclovir, cidofovir, foscarnet)
  • immunosuppressant (tacrolimus, cyclosporine, everolimus)
  • chemotherapy (cisplatin, ifosfamide, temsirolimus)

Radiographic features

Imaging demonstrates preserved renal parenchyma perfusion, but with minimal or absent excretion into the urinary collecting system.

Fluoroscopy / CT urography

Imaging with iodinated contrast typically demonstrates an immediate or mildly delayed nephrogram, but without excretion into the collecting system. Delayed 24 hour imaging would also demonstrate persistent nephrogram or striated nephrogram due to stasis of contrast within the renal tubules .

Ultrasound

Ultrasound is usually performed in this setting to assess the renal parenchyma and exclude other causes of obstruction. In acute tubular necrosis, the kidneys usually have a normal appearance on ultrasound, but may be enlarged and increased echogenicity .

Nuclear medicine

Renal scintigraphy can help differentiate acute tubular necrosis from other causes of renal failure such as renal cortical necrosis. It is also often used to evaluate renal transplants when there is a suspicion for acute tubular necrosis of the transplant. Renal perfusion is preserved during angiographic phase with a gradual increase of radiotracer due to minimal or absent excretion .