Acute Renal Failure/ AKI Flashcards
definition of AKI?
Acute renal failure
= absolute increase in serum creatnine of .3 mg/dL
= 50% increase in serum creatinine
= reduction in urine output consisting of oliguria of less than 0.5 mL/kg/hr for longer than 6 hours
signs of chronic renal failure
anemia, hyperparathyroidism (osteodystrophy), A/V fistula, Hyperphosphatemia
sediment on U/A
see casts, RBCs and WBCs = think acute renal failure
hyaline casts
seen in pre-renal AKI
- secreted from tubular epithelial cells, due to low urine flow, concentrated urine, acidic encironment, dehydration, etc.
muddy brown, granular, epithelial casts
intrarenal AKI, tubular cell injury
granular casts: second most common type of casts - result from breakdwon of cellular casts or inclusion of aggregates of plasma proteins
pyuria, hematuria, mild proteinuria, granular and epithelial casts, eosinophilia
intrarenal AKI: acute interstitial nephritis
hematuria, marked proteinuria, RBC casts, granular casts
intrarenal AKI: glomulonephritis
normal/hematuria, mild proteinuria
intrarenal AKI: vascular disorder
see normal or hematuria, granular casts and pyuria
postrenal AKI
waxy casts
represent end product of cast evolution, suggest very low urine flow associated w/ severe, longstanding kidney disease and renal failure
pre-renal
FeNa = 20:1
ATN
FeNa = >1%
urine sodium >20 (kidney is damaged, so urine sodium is high)
BUN:Cr : <20:1
toxic injury
> 1% FeNa
urine sodium >20 (kidney is damaged, so urine sodium is high)
BUN:Cr <20:1
glomerulonephritis
<20:1
vascular disorders
<20:1
damage of prerenal azothemia?
this is normal physio. response to dehydration, the kidney tries to keep the fluid, they will recover
causes of pre-renal azothemia?
Intravascular volume depletion and or hypotension
- Hemorrhage
- GI loss: vomiting/diarrhea
- Renal loss: diuretics, diabetes (mellitus and incipidus)
- Dermal losses (sweating)
Decreased effective intravascular volume
- Congestive heart failure
- Cirrhosis
- Hepatorenal syndrome,
- Peritonitis
Systemic vasodilation/renal vasoconstriction
- Sepsis
- Hepatorenal syndrome
Large-vessel renal vascular disease
- Renal artery thrombosis or embolism
- Renal artery stenosis
what meds make prerenal azothemia worse and may even push pt. into acute tubular necrosis?
NSAIDs: inhibit the production of prostaglandins which are natural dilators in response to hypoperfusion (they don’t constrict affarent arterioles, but NSAIDs keep prostaglandins from dilating them)
ACEIs and ARBs: dilate the efferent arterioles and drop perfusion pressure
cyclosproine, radiocontrast, tacrolimus
upper GI bleeds result in what?
super elevated BUN levels due to increased RBCs being broken down
acute interstitial nephritis
= hypersensitivity reaction
- has damaged kidneys, has extension after initiation phase, the kidneys must regenerate, so might see an increase in creatinine levels, even after tx.
- will go into maintenance phase and will stay the same b/c they are regenerating
- will see recovery and drop in creatinine levels in a week
difference: in pre-renal you give fluids and they are immediately better creatinine levels
nephrotoxic medications resulting in ARF?
Aminoglycosides Radiocontrast agents Acyclovir Cisplatin Sulfonamides Methotrexate Cyclosporine Tacrolimus Amphotericin B Foscarnet Pentamidine Ethylene glycol Toluene Cocaine HMG-CoA reductase inhibitors
Wegner’s granulomatosis vs. Goodpasture sx
Wegners: see ANCA
goodpastures: see anti-GBM
