Definition - Acute Renal Failure

Acute renal failure (ARF) Definition,:

• Abrupt deterioration in parenchymal kidney function, usually reversible. Clinically, damage should be enough to cause uraemia.
• Oliguria (dec. urine ouput) a feature usually.
• Can be life-threatening medical emergency due to drastic electrolyte imbalances.
• Acute vs chronic not readily apparent with pt. w/ uraemia. Note: acute-on-chronic cases exist
  

Acute Renal Failure

Pre-renal

Intrinsic

Post-renal

Pre-renal uraemia (impaired perfusion of kidneys with blood)

• hypovolaemia, hypotension, impaired cardiac pump efficiency, vascular disease limiting renal blood flow, combinations.
• usually can be autoregulated and GFR can be relatively maintained, progression leads to pre-renal uraemia.
  

Intrinsic uraemia (damage to the kidney itself)

• toxins/meds, rhabdomyolosis (breakdown of myocytes releases myoglobin which affects the kidney - can be caused by injury [especially crush or extensive blunt trauma]), haemolysis - resultant haemoglobin damages tubules, multiple myeloma, acute glomerulonephritis
  

Post-renal uraemia (obstruction in urinary tract from calyces to ext, urethral tract.)

• medication interfering with normal bladder emptying (e.g. anticholinergics).
• benign prostatic hypertrophy or prostate cancer.
• kidney stones.
• due to abdominal malignancy (e.g. ovarian cancer, colorectal cancer).
• obstructed urinary catheter.
• drugs that can cause crystalluria and drugs that can lead to myoglobinuria & cystitis