IM Renal ARF USMLE 2
Terms
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Dx:
Rapid onet of oliguria w/ increasing BUN and creatinine; often occurs in hospitalized patients - Acute Renal Failure
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ARF class:
weight loss or gain, poor skin turgor, edema/ascites, renal artery bruit - Pre-renal ARF
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ARF class:
weight gain, obtundation, hypotension to HTN, JVD, evidence of muscle trauma, infection, contaminated IV lines - Intrinsic ARF
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ARF class:
weight gain, enlarged prostate, pelvic mass, bladder distension - Post-renal ARF
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Etiology of pre-renal ARF
(4 and example of each) -
1. Hypovolemia
(including hemorrhage and GI loss)
2. Third-spacing
(including nephrotic syndrome, burns and cirrhosis)
3. Low cardiac Output
(including CHF and shock)
4. Renal hypoperfusion
(including renal artery stenosis, NSAIDs + ACEi) -
Etiology of Intrinsic ARF
(5) -
1. Hyperviscosity
(multiple myeloma)
2. Acute Tubular Necrosis
(due to: meds or rhabdomyolysis)
3. Glomerular injury
(Nephrotic syndrome, vasculitis, GN)
4. Acute Interstitial Nephritis
5. Renovascular infarction -
Etiology of Post-renal ARF
(3) -
1. Urinary tract obstruction
2. enlarged prostate
3. bladder dysfunction -
Define:
Oliguria - Urine output < 400 mL/day
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Indications for Dialysis:
(5) -
AEIOU:
Acidosis
Electrolyte abnormalities
Ingestions
Overload
Uremic symptoms (pericarditis, encephalopathy) -
Pre-renal amounts for:
1. BUN/creatinine ratio
2. Fe-Na
3. Urine Na
4. Urine Osmolality
5. Urine specific gravity -
1. > 20
2. < 1%
3. < 20
4. > 500
5. > 1.020 -
Intrinsic renal (ARF)amounts for:
1. BUN/creatinine ratio
2. Fe-Na
3. Urine Na
4. Urine Osmolality
5. Urine specific gravity -
1. < 20
2. > 1%
3. > 40
4. < 350
5. = 1.010 - What (2) Dx test and results point to a post-renal ARF problem?
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Fe-Ne > 4%
Urine Na > 40 - Equation for Fractional Excretion of Sodium (Fe-Na)
- Fe-Na = (urine Na/plasma Na) / (U-creatinine/P-creatinine) x 100%
- MCC of intrinsic ARF
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Tubulointerstitial diseases
(ATN and AIN) -
Dx:
Acute damage of renal tubules due to ischemic or toxic insult - Acute Tubular Necrosis
- Etiology of Ischemic (4) and Toxic (4) causes of ATN
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Ischemic:
Shock;
Trauma;
Sepsis;
Hypoxia
Toxic:
Rhabdomyolysis;
Aminoglycosides;
IV contrast;
Tumor lysis - (3) Dx findings for ATN
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Muddy-brown granular casts;
High urine sodium;
Fe-Na > 1% -
Tx for ATN
(4) -
- NS for volume replacement;
- IV diuretic in early stages;
- match I and O
- manage electolyte disturbance -
Dx:
Inflammation of the renal parenchyma - Acute Interstitial Nephritis
- (3) basic classes of etiologies of AIN
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Systemic diseases;
Systemic infections;
Medications - (3) systemic diseases that causes AIN
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Sarcoidosis;
Sjogren syndrome;
Lymphoma - (4) systemic infections (bugs) that cause AIN
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Syphilis;
Toxoplasmosis;
CMV;
EBV - (3) medication classes that can cause AIN
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Beta-blockers;
Diuretics;
NSAIDs - How do NSAIDs cause AIN?
- inhibit prostaglandin synthesis, which decreases GFR and start renal failure in pt w/ underlying renal problems
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Dx findings of allergic AIN
(3) -
WBCs;
Eosinophils;
White (or red) cell casts -
Tx of allergic AIN?
(2) -
1. stop offending agent
2. Steroids - initial microscopic finding in ATN
- blebbing of the PTC and loss of brush boarder
- microscopic finding of ischemic (2) ATN versus toxic
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Ischemic:
BM damage;
skipped areas of damage
Toxic:
no BM damage;
Uniform damage w/ sparing of DT -
Lab:
Oxalate crystal formation in kidney - Ethylene glycol ATN