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Acute kidney injury

Jul 25, 2019

Acute kidney disease is characterized by rapid decline of kidney function occurring within days. There are 4 stages:

  • Stage 1 – serum creatinine > 1.5 times the baseline or GFR reduced by > 25% or urine output < 0.5 ml/kg for 6 hours
  • Stage 2 – serum creatinine > 2 times the baseline or GFR reduced by > 50% or urine output < 0.5 ml/kg for 8 hours
  • Stage 3 – serum creatinine > 3 times the baseline or GFR reduced by > 75% or urine output < 0.3 ml/kg for 12 hours
  • Stage 4 – anuria (absence of urine)

Types of acute kidney injury:

  • Pre-renal – volume depletion, hypotension, infection.
  • Renal – toxins, NSAIDs, nephrotoxic drugs, acute tubular necrosis, glomerulonephritis.
  • Post-renal – renal stones, tumours, benign prostatic hypertrophy, urethral strictures, neurogenic bladder, hyperuricemia.

Treatment:

  • Hospitalize the patient, treat underlying cause of acute kidney injury and take nephrology opinion
  • Maintain adequate hydration and restrict fluid intake to urine output + 30ml per hour.
  • If patient is over hydrated (weight gain, limb edema, facial edema, abdominal distension) – Inj. Lasix (Furosemide) 20 mg to 40 mg i.v. repeat after 2 hours if desired effect not obtained.
  • Correct acid-base, urea and any electrolyte abnormality.
  • Consider dialysis if – serum creatinine > 10, uremia, severe acid base imbalance

Investigations:

  • Urine routine – to rule out haematuria, proteinuria or infections.
  • Complete blood count – to rule out infection or anaemia.
  • Serum electrolytes – to identify abnormalities. Serial results needed to assess effectiveness of treatment.
  • Serum uric acid – may be raised due to renal failure.
  • Peripheral smear -to rule out hemolysis.
  • Arterial blood gas – to look for metabolic acidosis.
  • USG KUB – to rule out stones, loss of corticomedullary demarcation.
  • Chest X ray – to rule out fluid overload causing pleural effusion.
  • Antinuclear antibody (ANA), Antineutrophil cytoplasmic antibody (ANCA) – to rule out connective tissue disease as a cause.
  • Anti-glomerular basement membrane antibody (Anti-GBM Ab) – to rule out glomerulonephritis.
  • Antistreptolysin O antibodies (ASO titre).
  • Complement levels – reduced levels are seen in autoimmune glomerulonephritis.

Referral:

Consider immediate referral to nephrologist for all cases.