21 - Nephrotoxicity Flashcards
Diagnostic criteria of acute kidney injury
- Abrupt decline in GFR
- sCr by 0.3 mg/dL or more w/in 48 h, OR
- sCr to 1.5 times or more baseline w/in 7 days, OR
- Urine volume < 0.5 mL/kg/h for 6 hours
Pre-renal AKI means ____
Impaired renal perfusion
Causes of pre-renal AKI
- Volume depletion (diuretics, cathartics, emetics)
- Bleeding (anticoagulants)
- Cardiac dysfunction (beta-blockers, cardiotoxins)
- Vasoconstriction (NSAIDs, calcineurin inhibitors, ex: cyclosporine)
Renal AKI means ____
Intrinsic damage
Causes of renal AKI
- Vascular -> cyclosporine, tacrolimus, quinine, clopidogrel
- Glomerular (ACE inhibitors, NSAIDs)
- Acute tubular necrosis (acetaminophen, aminoglycosides, antifungals, chemotherapeutic agents, iodinated contrast media)
- Acute interstitial nephritis (hypersensitivity) -> antimicrobials, NSAIDs, diuretics, antihistamines, PPI
What is the most common cause of AKI?
Pre-renal
Post-renal AKI means ____
Obstruction of urine flow
Causes of post-renal AKI
- Bladder dysfunction (anticholinergics, antipsychotics)
- Crystal forming (acyclovir, ciprofloxacin, methotrexate, sulfonamides)
- Retro-peritoneal fibrosis (beta-blockers, bromocriptine, hydralazine, methyldopa)
Risk factors for chronic kidney disease
- Pre-existing renal impairment
- Dehydration (diuresis, vomiting or diarrhea, hemorrhage)
- Medical conditions (cirrhosis, HF, DM)
- Multiple nephrotoxic agents
- Seriously ill (septic shock, hypotension)
- Advanced age
Which NSAIDs are most nephrotoxic?
All equally nephrotoxic
Mechanism of NSAID nephrotoxicity
- Pre-renal (decreases vasodilatory prostaglandins => vasoconstriction => decreased renal blood flow)
- Acute interstitial nephritis
Clinical manifestations of NSAID nephrotoxicity
- Increased plasma creatinine
- Decreased renal blood flow and GFR
- Oliguria
Prevention of NSAID nephrotoxicity
- Avoid NSAIDs among high-risk px
- Monitor creatinine levels closely
- Avoid NSAIDs prior to procedures involving radiocontrast
Mechanism of aminoglycoside nephrotoxicity
- Proximal tubular necrosis
- Interstitial nephritis
Clinical manifestations of aminoglycoside nephrotoxicity
- Increased plasma creatinine
- Increased BUN
- Non-oliguric
- Electrolyte abnormalities (infrequent)
Aminoglycoside-related risk factors for nephrotoxicity
- Elevated serum drug concentrations
- Prolonged duration of therapy
- Type of aminoglycoside (gentamicin > tobramycin > amikacin)
- B/c gentamicin has highest affinity
- Frequency of dosing (once daily vs. traditional dosing)
Prevention of aminoglycoside nephrotoxicity
- Avoid in px w/ risk factors
- Adjust dose for renal function
- Correct hypokalemia and hypomagnesemia
- Limit duration of therapy to 7-10 days
- Minimize concomitant nephrotoxic medications
- Choose aminoglycoside w/ less nephrotoxicity
- Monitor aminoglycoside serum concentration
- Utilize a once-daily dosing regimen
Mechanism of iodinated contrast media nephrotoxicity
High osmolality => acute tubular necrosis and vasoconstriction
What are properties of the newest iodinated contrast media?
- Non-ionic dimers
- Iso-osmolal
Clinical manifestations of iodinated contrast media nephrotoxicity
- Within 24-48 h after exposure
- Mild increase in sCr
- Usually non-oliguric
- Hyperkalemia, acidosis, hyperphosphatemia
Dye-related risk factors for iodinated contrast media nephrotoxicity
- Dose of contrast agent
- Type of contrast agent
- Specific procedure (intra-arterial vs. IV and interventional vs. diagnostic angiography)
Pt-related risk factors for iodinated contrast media nephrotoxicity
- GFR < 60 mL/min + significant proteinuria (proteinuria > 500 mg/day)
- GFR < 60 mL/min + comorbidities (DM, HF, liver failure, or multiple myeloma)
- GFR < 45 mL/min
- GFR < 30 mL/min (highest risk)
Prevention of iodinated contrast media nephrotoxicity
- Avoid volume depletion
- Withhold NSAIDs for 24-48 h prior to procedure
- Dose and type of contrast agent:
- Use lowest effective dose
- Avoid high osmolality agents, use iso-osmolal agent or nonionic low-osmolal agents (2nd or 3rd gen agents)
- For at-risk px/risky procedures -> hydrate w/ IV isotonic saline