Acute Kidney Injury Flashcards
What is the KDIGO criteria for AKI?
- Increase in serum creatinine >= 0.3 mg/dL
- Increase in serum creatinine 1.5x or more than baseline of the prior 7 days
- Urine volume < 0.5 mL/kg/h for at least 6 hours
which of the 3 KDIGO criteria is most often used clinically?
creatinine 1.5x or > than baseline of the prior 7 days
what are two signs that might point you towards AKI in a patient on first presentation?
- increased creatinine (however may look normal in early stages)
- decreased urine volume (more present in early stages)
define AKI
a sudden and often reversible reduction in kidney function
what is the RIFLE criteria?
levels of impairment
- R - risk of impairment
- I - injury to kidney
- F - kidney failure
categories of LT renal outcomes
- L - loss of kidney function over 4 wks
- E - end-stage renal disease
who is AKI most common in?
hospitalized pts in ICU
what is the most common cause of AKI in hospitalized pts?
transient renal hypoperfusion resulting in ischemic acute tubular necrosis or ischemic intrarenal AKI
what are some causes of prerenal AKI?
general: any cause of reduced blood flow to the kidney
- Hypovolemia: diarrhea, vomiting, hemorrhage, severe burns
- Relative fluid loss: third spacing ➔ sepsis, CHF, liver failure, anaphylaxis
- Blockage of renal artery: renal artery stenosis, compression, blood clot
- Medications: NSAIDs and ACEi
what are some causes of intrarenal AKI?
these are conditions that impact the glomerulus, tubules, interstitium or the vasculature
Tubular: 1) acute tubular necrosis ➔ caused by prolonged renal ischemia, sepsis, nephrotoxins; 2) intratubular obstruction ➔ casts that obstruct the tubules
Glomeruli: glomerulonephritis
interstitium: acute interstitial nephritis ➔ type I and IV hypersensitivity rxns to medications like antibiotics, NSAIDs, PPIs, and 5-ASA, autoimmune, hereditary
Vascular: microangiopathies ➔ vascular obstruction ➔ HUS, TTP, HTN emergency
What are some causes of postrenal aki?
Obstructive causes which lead to congestion and urinary backflow, usually a bilateral obstruction
obstruction: stones, neurogenic, phimosis, thrombus
compression: fecal impaction, tumours, prostate hyperplasia, retroperitoneal fibrosis, pelvic organ prolapse or masses
most common 3 causes of intrarenal AKI
- prolonged renal ischemia
- sepsis
- nephrotoxins
explain the patho for prerenal AKI
- decreased perfusion to kidney
- renal cell damage bc lack of O2 and nutrients from kidney hypoperfusion
- decreased eGFR
- build up of fluid/waste products in blood
- activation of RAAS
- sodium retention and water reabsorption ➔ HTN
would you expect urine osmolarity to be high in prerenal AKI or low? why?
would be high, kidney is still able to concentrate the urine and reabsorb sodium and water
explain the patho for intrarenal AKI
- damage to the podocytes and tubular cells ➔ increased membrane permeability and impaired reabsorption/secretion
- fluid overload in tubules
- sloughing of casts ➔ blocks tubules/obstruction
- overall reduced pressure difference in glomerulus and bowman’s capsule bc build of pressure
- not enough pressure gradient to drive filtration
- decreased eGFR and fluid/wastes stay in blood
would you expect urine osmolarity to be high in intrarenal AKI or low? why?
would be low, not able to concentrate urine anymore because tubules are damaged, also decreased filtration rate because less pressure difference
