Acute Tubular Necrosis

(ATN)

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Definition

-  Usually reversible abrupt (hrs-wks) decline in renal function --> elevated Urea & Cr secondary to renal tubular cell death

 

Features

-  Most common renal cause of ARF

-  2nd most common cause of ARF in hospitalised pts

-  In hospital mortality 50%

-  May progress to CRF

-  Initiation

-  Acute decrease in GFR

-  Elevated Urea & Cr

-  Maintainance

-  Decreased GFR for 1-2/52

-  +/- oliguria

-  Recovery

-  Increased urine volume

-  Decreasing Urea & Cr

 

Causes

-  Toxic

-  Rhabdomyolysis

-  Antibiotics

-  Aminoglycosides

-  Ethylene glycol (anti-freeze)

-  Ischaemic

-  Pre-renal ARF

 

Associated S/S

-  Oliguria

-  Urinary casts +/- debris

-  Hyperkalaemia

-  Hyponatraemia

-  Hyperphosphataemia

-  Hypermagnesaemia

-  Hypocalcaemia

-  Metabolic acidosis

-  HTN, oedema, CCF

 

Ix

-  FBE

-  U&E

-  CMP

-  Uric Acid

-  Urinalysis

-  Muddy brown granular casts 70-80%

-  Fractional excretion of Na: DDx pre-renal

-  Urine osmolarity

-  Renal US: exclude obstruction

 

DDx Pre-renal ARF

-  Pre-Renal

-  Urine Osmol >500

-  Urine Na <20

-  Fractional Na <1

-  Fractional Urea <35

-  Bland urinary sediment

-  ATN

-  Urine Osmol <350

-  Urine Na >40

-  Fractional Na >2

-  Fractional Urea >50

-  Muddy brown granular casts

 

Mx

-  +/- IV fluids

-  Cease nephrotoxic meds

-  If Oliguria Frusemide 100-200mg IV single dose

-  ONLY if vol & cardio status allow

-  Controversial

-  Mx of metabolic abnormalities

-  Adjust other meds as per renal function

-  Haemodialysis as needed