Acute Tubular Necrosis

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Acute Tubular Necrosis
2011-05-08 16:02:46

For my upcoming nephrology exam
Show Answers:

  1. What is ATN?
    • Acute kidney injury from ischemia or toxin
    • Ischemia frmo hypoperfusion or hypoxemia
  2. What causes ATN?
    Shock, sepsis, or hypovolemia
  3. What are the three phases of ATN?
    • Initial (injury)
    • Maintenance (Lasts 1-3 weeks to a couple of months): cellular repair is starting to occur, removal of any tubular debris or necrotic materials
    • Recovery: diuresis occurs, BUN and Cr fall, GFR increases
  4. Name 3 exogenous nephrotoxins causing ATN
    • Aminoglycosides
    • Contrats
    • Cyclosporines
  5. Name 4 endogenous nephrotoxins causing ATN
    • Myoglobinuria
    • Hemoglobin
    • Hyperuricemia
    • Bence Jones proteins
  6. What increases the risk for aminoglycosides causing ATN?
    • Age
    • Underlying kidney dz
    • Hypovolemia
    • Age
  7. What is the least nephrotoxic aminoglycoside?
  8. When does aminoglycoside toxicity occur and how long does it last?
    5-10 days after exposure, and can be present in renal tissue for one month
  9. When does contrast toxicity occur?
    Within 24-48 hours of study
  10. How can you prevent ATN caused by contrast?
    • N-acetylcystine
    • HCO3
    • Avoiding contrast
  11. How does cyclosporine cause ATN?
    • It causes severe vasoconstriction and therefore tubular dysfunction
    • dose dependent, so lab monitoring is important
  12. Dark urine without RBCs signifies what?
    Myoglobinuria due to rhabdo
  13. What can cause myoglobinuria?
    • Rhabdo
    • Chronic EtOH
    • Seizures
    • Prolonged dehydration
  14. What are s/sx of ATN?
    • Azptemia
    • N/V/malaise
    • AMS
    • HTN
    • pericardial effusions
    • arrhythmias (from hyperkalemia)
    • Nonspecific diffuse abdominal pain
  15. What do labs show?
    • Hyperkalemia
    • Hyperphosphatemia
    • BUN:Cr <20:1
    • Decreased urine volume
  16. What does a UA show?
    Brown, granular casts with renal tubular epithelial cells
  17. How do you tx?
    • Nephrology referral always
    • Furosemide (to address hyperkalemia, but can worse prognosis)
    • Chlorothiazide IV 250-500 mg q8-12h
    • Calcium supplementation
    • Aluminum hydroxide
  18. When do you put an ATN pt on dialysis?
    • Life-threatening hyperkalemia
    • Worsening acidosis
    • No reponse to diuretics
    • complications of uremia (encephalopathy, pericarditis, seizures)
  19. What gives a worse prognosis?
    • Oliguric maintenance phase
    • Older age, severe underlying dz, multiorgan involvement