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What is ATN?
- Acute kidney injury from ischemia or toxin
- Ischemia frmo hypoperfusion or hypoxemia
What causes ATN?
Shock, sepsis, or hypovolemia
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
Name 3 exogenous nephrotoxins causing ATN
Name 4 endogenous nephrotoxins causing ATN
- Bence Jones proteins
What increases the risk for aminoglycosides causing ATN?
- Underlying kidney dz
What is the least nephrotoxic aminoglycoside?
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
When does contrast toxicity occur?
Within 24-48 hours of study
How can you prevent ATN caused by contrast?
- Avoiding contrast
How does cyclosporine cause ATN?
- It causes severe vasoconstriction and therefore tubular dysfunction
- dose dependent, so lab monitoring is important
Dark urine without RBCs signifies what?
Myoglobinuria due to rhabdo
What can cause myoglobinuria?
- Chronic EtOH
- Prolonged dehydration
What are s/sx of ATN?
- pericardial effusions
- arrhythmias (from hyperkalemia)
- Nonspecific diffuse abdominal pain
What do labs show?
- BUN:Cr <20:1
- Decreased urine volume
What does a UA show?
Brown, granular casts with renal tubular epithelial cells
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
When do you put an ATN pt on dialysis?
- Life-threatening hyperkalemia
- Worsening acidosis
- No reponse to diuretics
- complications of uremia (encephalopathy, pericarditis, seizures)
What gives a worse prognosis?
- Oliguric maintenance phase
- Older age, severe underlying dz, multiorgan involvement