Acute Renal Failure Flashcards
Acute kidney injury
abrupt decline in renal function manifesting as reversible acute increase in nitrogenous wastes over hours to weeks
What are the 3 graded levels of acute injury to the kidney (RIFLE criteria)
risk, injury, failure
What are the 2 outcome measures in the RIFLE criteria
loss of function and end stage renal disease
What is the RIFLE criteria based on
either degree of serum creatinine elevation or decrease in urine output
What conditions put a patient at a high risk of developing AKI
- HTN
- CHF
- DM
- multiple myeloma
- chronic infection
- myeloproliferative disorder
What are the three categories of causes of AKI
- prerenal causes (low flow)
- intrinsic causes (problem with actual kidney)
- post renal cause (flow obstruction)
Prerenal causes of AKI
- hypovolemia
- decreased cardiac output
- decreased effective circulating volume
- impaired renal autoregulation (NSAIDs, ACE/ARB, cyclosporine)
What is azotemia
increased in BUN and creatinine
What causes most AKI
low flow state (prerenal cause)
Pre-renal AKI results from what? What can be done to reverse it?
results from poor renal perfusion
can be reversed with restoration of renal perfusion/glomerular pressure
BUN/Creatinine ratio would be what in pre-renal injury
20:1
What would a urinalysis show in pre- renal injury
hyaline casts
What is the breakdown of intrinsic causes of AKI
- glomerular
- tubules and interstitium
- vascular
What does calculation of FeNa tell you
where the renal failure is occuring
<1% prerenal
>1% intrinsic
>4% post renal failure
When is the calculation of FeNA not accurate
when pt takes diuretics
What is the alternative to FeNa
FeUrea
<35% prerenal
>50% suggests acute tubular necrosis
Labs for prerenal AKI if due to volume depletion. Decreased CO.
Volume Depletion:
- elevated H/H, albumin, calcium (hemoconcentration)
- elevated Na, BUN, Cr
Decreased CO
- edema
- low Na, albumin
Urine
- oliguria or anuria
- high urine specific gravity
- low urine Na
Treatment for prerenal AKI caused by volume depletion. Decreased CO.
Volume depletion:
-correct water deficit, NS
Decreased CO:
- diuretics
- nitrates
- dobutamine
What are some intrinsic causes of AKI
- acute interstitial nephritis
- acute tubular necrosis
- glomerular diseases
- pyelonephritis
- malignancy
- renal artery embolism/thrombus
- vasculitis
What is acute interstitial nephritis typically due to
allergic reaction to medication
What is the classic presentation of acute interstitial nephritis
- recent new drug exposure
- fever
- skin rash
- peripheral eosinophelia
- oliguria
How do patients more commonly present with acute interstitial nephritis
found incidentally, rising serum creatinine after initiation of a new med
What medications are associated with acute interstitial nephritis
- abx (b-lactams, sulfonamides, vanco, erythro, rifampin)
- acyclovir
- NSAIDs
- anticonvulsants
Acute interstitial nephritis urinalysis
- pyuria (WBC casts)
- hematuria
Treatment of acute interstitial nephritis
- discontinue offending agent
- glucocorticoid therapy (prednisone, methylprednisolone)