Acute Kidney Injury Flashcards
What elements are used to calculate the MDRD to estimate GFR?
- serum creatinine
- age
- female or not
- african american or not
What elements are used to calculate the cockroft gault equation to estimate GFR?
- age
- ideal body weight
- serum creatinine
- female or not
Using the microalbumin/creatinine ratio, how do you define normal, microalbuminuria, macroalbuminuria?
< 30 mg/g - normal
30-300 mg/g - microalbuminuria
> 300 mg/g - macroalbumuria
Criteria for AKI
One of the following
- increase in serum creatinine of > 1.5 times baseline within prior 7 days
- increase in serum creatinine of > 0.3 mg/dL within 48 hours
- Urine volume < 0.5 mL/kg per hour for more than 6 hours
Most common cause of AKI
Acute tubular necrosis - 45%
most often caused by hypotension/sepsis, ischemia, surgery/burns, nephrotoxins, rhabdo
What is acute interstitial nephritis (AIN), how is it diagnosed, and how is it treated?
fever, rash, elevated serum and urine eosinophils
most common cause is medication, also infection, autoimmune disease, infection
Tx: immediate withdrawal of drug and supportive care are essential
- corticosteroids may be beneficial
Drugs commonly associated with acute interstitial nephritis
PPI allopurinol cimetidine NSAIDs phenytoin Diuretics - thiazides, furosemide sulfonamides cephalosporins, rifampin, cipro, PCN
What is the clinical picture of nephritic syndrome?
- RBCs/RBC casts
- hypertension
- mild proteinuria
What is the clinical picture of nephrotic syndrome
- massive proteinuria
- edema/hypoalbuminemia
- hyperlipidemia
- hypercoagulable
When someone has postrenal AKI, what additional evaluation is warranted
renal US to look for hydronephrosis
When should renal biopsy be performed in setting of AKI?
- Clinical findings: oliguria, rapidly worsening GFR
- cause of intrinsic injury unclear
- pre-renal and post-renal causes have been ruled out
- need for confirmation before disease specific therapies commence
How do you manage at-risk patient before a dye study?
- stop metformin 48 hours before, esp if GFR < 60
- isotonic solution IV hydration
- acetyle cysteine 120 mg BID he day before and the day of exam (inconsistent data)
- high dose statins may be helpful
- alkalinize the urine (inconsistent data)
When prescribing metformin, how do you use renal function to guide management?
- do not start if eGFR < 45
- at eGFR < 45 may continue previous therapy but may consider 50% reduction in dose
- do not use if GFR < 30
When prescribing nitrofurantoin, how do you use renal function to guide management?
Avoid using in GFR < 60 ml/min
What lab findings are used to calculate FENa? How do you interpret FENa?
FENa = 100 x (urine Na X Plasma Cr)/(plasma Na x Urine Cr) prerenal = < 1 % renal = 1-2% ATN = > 2-3%
components of FeUrea
How do you interpret it?
BUN, serum cr, urine urea, urine creatinine
FeUrea < 35% - prerenal
FeUrea > 50% - ATN
How do you calculate mean arterial pressure (MAP)?
MAP = (systolic + 2x diastolic)/3
Treatment of AKI with volume overload
Lasix IV Q6 is initial tx
If inadequate response after 1 hr double the dose
repeat until adequate urine output
Treatment of hyperkalemia
- IV calcium gluconate (cario protective/membrane stabilizer)
- Shift K into cells: insulin (10 units IV and glucose 25 gm), albuterol, sodium bicarb (3 amps in 1 L of 5% dextrose
- eliminate: Oral or rectal Kayexelate
In acidosis, what lab finding would prompt you to initiate sodium bicarb
Serum bicab < 15 mEq/L or pH < 7.2
What are indications for emergent dialysis in patients with AKI?
- metabolic acidosis: ph < 7.1
- Uremia: pleuritis, pericarditis, neuropathy, encephalopathy/aMS
- fluid overload refractory to diuretics
- Hyperkalemia: K > 6.5 of rapid rise
- poisoning
What level of metabolic acidosis should prompt urgent dialysis in renal failure?
- metabolic acidosis: ph < 7.1
What potassium level should prompt urgent dialysis in renal failure?
- Hyperkalemia: K > 6.5 of rapid rise
What is Cardiorenal syndrome type I?
Acute CHF causes acute AKI
