Classification
What is the definition of an AKI?
Increase of serum creatinine of greater than 0.3 over 48 hours or a greater than 50% increase over 1 week
What are some examples of prerenal, intrinsic and postrenal causes?
Prerenal: hypovolemia, severe HFrEF, decompensated cirrhosis
Intrinsic: ATN, AIN, tumor lysis syndrome
Postrenal: obstruction (BPH, cancer)
Name 2 common medications that can cause acute interstitial nephritis.
PCNs, cephalosporins, sulfas, cipro, NSAIDs, PPIs, acyclovir, rifampin, phenytoin, interferon
Name some medications that should be stopped to avoid aggravating AKI.
NSAIDs, ACE inhibitors, ARBs, metformin, gabapentin, cefepime, morphine, zosyn
How many stages are there of AKI according to KDIGO guidelines
3 stages
What percent of community and hospital acquired AKIs are due to prerenal causes?
70/40
What is the classic triad of symptoms for AIN?
Maculopapular rash, fever, arthralgias
All 3 only present in 1/3 of cases
What are the increases of creatinine for each stage?
Stage 1: 1.5-1.9 times baseline
Stage 2: 2-2.9 times baseline
Stage 3: greater than 3 times baseline or Cr over 4
What is the most common cause of intrinsic AKI and hospital acquired AKI
Acute tubular necrosis due to sepsis, shock, etc
How long after taking the offending medication dose AIN present?
1 day to several weeks depending on medication
8 days for PCNs
weeks to months for NSAIDs
Is there a medication you can take to help treat ATN?
No, KDIGO 2012 guidelines show that the previous thought of diuretics being helpful by increasing urine output was clinically insignificant
What are the urine outputs for each stage?
Stage 1: Urine volume <0.5 mL/kg/hr for less than six hours
Stage 2: Urine output of <0.5 mL/kg/hour for 12 to 24 hours
Stage 3: Urine output of <0.3 mL/kg/hour for >24 hours or anuria for >12 hours
What is the demographic of patients most likely to develop AKI due to UTI?
Older men with prostate disease
What does a UA look like in AIN patients?
pyuria, proteinuria, white cell casts
urinary eosinophils are neither sensitive or specific