Acute tubular necrosis

- usually arises following an acute ischemia or nephrotoxic event
- characterised by 3 phases
  i) initiation phase: acute decrease in GFR with sudden rise in creatinine
  ii) maintenance phase: sustained marked reduction in GFR
  iii) recovery phase: tubular function gradually restored with concomittant reduction in creatinine
- pigmented 'muddy brown' granular cast are characteristic of ATN and depict sloughed tubular epithelial cells
- reduced urinary osmolality < 350mOsm/kg (reduced tubular function and reduced filtration rate)
- raised urinary sodium concentration > 40mmol/L (decreased tubular reabsorption of sodium)
- associated with accelerated hypertension, hypotension, diabetes, liver failure, eclampsia, aminoglycosides.