Acute kidney injury N17.9

The current diagnosis of Acute Renal Failure is based on the 2012 KDIGO criteria (Kidney Disease: Improving Global Outcome") and is considered to be present if one of the following criteria is met:

• Increase in serum creatinine by ≥0.3 mg/dL (26.5 μmol/L) within 48 hours

• Increase in serum creatinine to ≥1.5-fold within the last 7 days

• Newly occurred reduction of the urine quantity <0.5 mL/kgKG/h over 6 hours

Prerenal acute renal failure (60%):

• Decreased perfusion is the cause of loss of function, e.g. due to hypovolemia or decreased circulating blood volume for example in the context of shock, sepsis or nephrotic syndrome. Prolonged prerenal genesis may additionally lead to intrarenal renal failure due to tubular necrosis.

Intrarenal acute renal failure (35%); the cause is O2 deficiency of the renal parenchyma due to reduced perfusion:

• tubular causes:
  • Acute tubular necrosis (mainly) due to ischemia or drug toxicity.
  • Pigment nephropathy for example due to hemolysis or rhabdomyolysis (crush syndrome)
• macrovascular causes:
  • Renal vein thrombosis
  • Renal artery stenosis
  • Renal infarctions
  • Arterial dissections
• microvascular/glomerular causes:
  • Glomerulonephritides
  • thrombotic microangiopathies (e.g. HUS, HELP syndrome)
  • cholesterol embolism
  • local bacterial infections

Postrenal acute renal failure (5%)

• an outflow obstruction is the cause of acute renal failure (acquired: e.g. renal pelvic stones, tumors or congenital: e.g. urethral strictures, bladder malformations)

The clinical picture of acute renal failure is non-specific. Asymptomatic courses are possible.

Possible leading finding: oligo- or anuria .

Three phases of acute renal failure are described (Herold 2019):

• Asymptomatic initial phase or symptoms of the underlying condition.
• Manifest renal failure phase characterized by increase in retention parameters.
• Diuretic/polyuric phase

Diagnosis based on the amount of urine excreted or the increase in creatinine.

Staging according to KDIGO

Determination of the cause by:

• anamnesis (loss of fluid, intake of nephrotoxic drugs...)
• physical examination (signs of hypervolemia, hypovolaemia)
• Laboratory (blood: creatinine, urea, electrolytes, blood count, BGA, CK, LDH, lipase, possibly BK, electrophoresis; urine: urine sediment, urine status, determination of fractional sodium excretion to differentiate between prerenal and intrarenal acute renal failure)
• Imaging mainly by sonography
• Renal biopsy to exclude a rapid progressive form

• fluid lung, pleural effusions
• Anemia, Uremia
• upper gastrointestinal bleeding
• Cardiac arrhythmias, pericarditis
• encephalopathy, seizures
• Infections, sepsis

• Treatment of the underlying disease,
• Avoid nephrotoxic drugs
• Balanced volume output
• depending on the genesis: immunosupressive therapy, revascularization, removal of the obstruction
• renal replacement therapy if necessary

1. Gudsoorkar PS et al (2019) Acute Kidney Injury, Heart Failure, and Health Outcomes. Cardiol Clin 37:297-305.
2. Zarbock A et al. (2014) New KDIGO guidelines on acute kidney injury. Practical recommendations.
   Anaesthesiologist 63:578-88.