Acute kidney injury N17.9

Co-Autor: Conrad Hempel

All authors of this article

Last updated on: 29.10.2020

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Synonym(s)

Acute renal failure; AKI; ANV

Definition
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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

Classification
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Stages of acute kidney failure after KDIGO 2012
Stadium Serum Creatinine Urinary excretion
1

1.5 to 1.9 times increase (within 7 days)

or

Increase by 0.3 mg/dL (26.5 μmol/L) (within 48 hours)

<0.5 mL/kgKG/h for 6-12 h

2

2 to 2.9 times increase (within 7 days)

<0.5 mL/kgKG/h for ≥12 h

3

≥6-fold? increase (within 7 days)

or

Increase to ≥4 mg/dL (353.6 μmol/L)

or

Start of a renal replacement therapy or

Patients <18 years: decrease of eGFR to <35 mL/min/1.73 m2

<0.3 mL/kgKG/h for ≥24 h

or

Anuria for ≥12 h

Etiology
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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)

Clinical picture
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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
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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

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

Therapy
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  • 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

Literature
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  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.

Authors

Last updated on: 29.10.2020

Co-Autor: Conrad Hempel Conrad Hempel