Acute tubular necrosis ATN

• Facts:
  Usually from prolonged hypotension
• Diagnosis:
  Muddy brown granular casts
  BUN/Cr ratio < 20:1
  Urine osmolality of 300-350 mOsm/L
  Urine Na > 20 mEd/L
• Differential Diagnosis:
  Glomerulonephritis (RBC casts)
  Interstitial nephritis and pyelonephritis (WBC casts)
  Nephrotic syndrome (fatty casts)
  Chronic renal failure (broad and waxy casts)