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)
What is acute tubular necrosis
acute tubular cell injury
What causes acute tubular necrosis
- ischemia
- sepsis
- toxins (exogenous, endogenous)
What are some nephrotoxins that can cause acute tubular necrosis
- NSAIDs
- chemotherapeutic agents
- aminoglucosides
- amphotericin
- vanco
- radiocontrast dye
Acute tubular necrosis on urinalysis
pigmented granular casts (muddy browncasts)
Lab findings with acute tubular necrosis
- Cr/BUN elevation
- FeNa >2%
- hyperkalemia
- hyperphosphatemia
- hyperuricemia
Treatment of acute tubular necrosis
- aggressive volume replacement
- high dose loop diuretic if oliguric and volume normal
- protein restriction
- dialysis
What is post-streptococcal glomerulonephritis
immune complex containing strep Ag is deposited in affected glomeruli
PSGN occurs __ days following ___
7-12 days following sore throat/impetigo
Findings of PSGN
- oliguria
- cola colored urine
- edema
- hypertension
- malaise, anorexia, flank pain
Tx of PSGN
- abx
- subbortive (anti HTN, salt restriction, diuretics)
Urinalysis of PSGN
- proteinuria
- hermaturia
- pyuria
- +/- RBC casts
What is necessary for a diagnosis of PSGN
recent group A beta-hemolytic strep infection
What is IgA nephropathy
deposition of IgA in the glomerulus often following a URI
How does IgA nephropathy present
- red or cola colored urine
- spectrum of glomerulonephritis
How do you diagnose IgA nephropathy
renal biopsy
How do you treat IgA nephropathy
- ACE/ARB
- steroids
- renal transplant
What is Henoch Scholein purpura
small vessel vasculitis w/ IgA complex deposition
How does HSP affects
children around 6
Classic clinical presentation of HSP
- rash on LE and buttocks
- abd pain/vomiting
- arthralgias (knees, ankles)
- edema on hands, feet, scalp, ears
Tx of HSP
- mostly supportive
- immunosuppressants and/or plasmapheresis for worsening disease
Three main findings with nephrotic syndrome
- heavy proteinuria
- hypoalbuminemia
- peripheral edema
Other findings in nephrotic syndrome
-lipiduria
-hypercholesterolemia
-hypertension
-hypercoagulable state
0blan urinary sediment
What things can cause nephrotic syndrome
- membranous nephropathy
- minimal change disease
- amyloidosis
- lupus
- membranoproliferative glomerulonephritis
- focal segmental glomerulosclerosis
- IgA nephropathy
Characteristic histologic finding of minimal change disease
diffuse effacement of the epithelial cell foot processes on electron microscopy
Signs of minimal change disease
- abrupt onset edema and nephrotic syndrome
- hypoalbuminemia
- HTN
- proteinuria (10g/day)
inimal change disease causes patients to be more susceptible to what
infection with gram + organisms
What is the most common cause of AKI in children
PSGN
How do you treat minimal change disease
prednisone
Causes of post renal AKI
- bladder outlet obstruction
- -neurogenic bladder
- gynecologic surgery or abdominopelvic malignancy
- pregnancy
- medications
Treatment of postrenal AKI
relief of obstruction (bladder cath, nephrostomy tube)
What is polycystic kidney disease
progressive genetic disorder with cyst formation and enlargement of the kidney
What other organs does polycystic kidney disease affect
pancreas, liver, spleen
Patients with polycystic kidney disease are at a 2x greater risk for what
intracranial aneurysm
Most patients with polycystic kidney disease require what
kidney transplant
Signs and sx of polycystic kidney disease
- pain (abd, flank, back)
- hypertension
- palpable flank mass
- nodular hepatomegaly
How do you diagnose polycystic kidney disease
- ultrasound
- elevated H/H
- urinalysis
How do you treat polycystic kidney disease
- ACE/ARB
- pain control (no nsaids), surgical cyst decompression, nephrectomy
- treat recurrent infections
- hydrate and possibly transfuse if hematuria
Signs and sx of vascular AKI
- LE rash
- livedo reticularis
- urine eosinophils
When do you dialyze a patient
acidosis electrolytes: hyperkalemia, hyperphosphatemia, hypocalcemia
Ingestion of toxins
Volume overload + anuria
Symptoms of Uremia
