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%):

• Reduced perfusion is the cause of loss of function, e.g. due to hypovolaemia or reduced circulating blood volume, for example in the context of shock, sepsis or nephrotic syndrome. A long-lasting prerenal genesis can additionally lead to intrarenal kidney versgene through tubule necrosis.

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

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

Postrenal acute kidney failure (5%)

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

The clinic of acute kidney failure is non-specific. Asymptomatic courses are possible.

Possible leading finding: oligo- or anuria

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

• asymptomatic initial phase or symptoms of the underlying disease
• Phase of manifest renal failure characterised by an increase in retention parameters
• Diuretic/polyuretic 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.