Acute Kidney Injury Flashcards
what is this?
muddy brown cast of acute tubular necrosis (ATN)
what is this?
RTE cell casts
pathomneumonic for ATN
prerenal azotemia vs. ATN
compare: urine osmolality, urine [Na+], fractional excretion of sodium, ratio blood urea nitrogen/creatinine, urine microscopy
3 causes of toxic ATN
- aminoglycosides
- iodinated radiocontrast
- amphotericin B
allergic interstitial nephritis
hypersensitivity rxn to NSAIDs, penicillin, diuretics
–> intra-renal azotemia
presents w/ oliguria, rash, fever days to weeks after starting drug w/ eosinophils in urine
usually resolves, but may progress to renal papillary necrosis - can tx w/ glucocorticoids in severe cases
WBC casts in acute interstitial nephritis
eosinophils in kidney in acute interstitial nephritis
rhabdomyolysis
can result in toxin-associated AKI
two mechanisms: 1. afferent arteriolar vasoconstriction 2. direct toxicity to RTE
pink urine: heme but w/ no RBCs, but clear serum
Light chain nephropathy - myeloma kidney (brittle casts w/ intense inflammatory response)
Light chains precipitate in tubules –> myeloma cast nephropathy
uric acid and tumor lysis symptoms
uric acid is toxic to RTE
distal tubular toxins (exogenous)
amphotericin B
cisplatinum
AKI caused by crystals
causes obstruction of tubular flow and sometimes inflammatory response
- acyclovir, indinavir, sulfadiazine, methotrexate
how does injury to tubular cells result in decreased GFR?
- tubuloglomerular feedback: impaired tubular function –> more glow reaches DT –> JGA senses this and constricts afferent arteriole
- back pressure –> injured cells form a plug
- back leak thorugh holes in tubular basement membrane
vascular causes of intrinsic AKI
large vessels: renal artery and vein
small vessels: thromboic microangiopathies
obstructive AKI
freq non oliguric
reduced GFR b/c decreased flow in medullary capillaries
dx: ultrasound to look for obstruction
