Management of Acute Kidney Injury (AKI)

Introduction

The definition of an acute kidney injury (AKI) is an abrupt and sustained decline in glomerular filtration rate (GFR). If creatinine is rising, GFR may be close to zero and therefore eGFR is of no value in the assessment of AKI. AKI is classed into three stage (see table 1). 

Table 1 – Stages of AKI

Common risk factors for AKI are listed in box 1. N.B. This list is not exhaustive.

Box 1 - Common risk factors for AKI

Other risk factors for AKI include:

• Hypotension
• Hypovolaemia
• In the setting of acute illness, certain drugs (ACE inhibitors, angiotensin receptor blockers, non-steroidal anti-inflammatory drugs (NSAIDs) and contrast may predispose to AKI.

Aetiology of AKI

• Pre-renal – hypotension, hypovolaemia, sepsis, drugs, contrast
• Renal – glomerulonephritis (GN) and vasculitis
• Post-renal – obstruction.

Assessment and Monitoring

If a patient has an AKI, consider RENAL:

• Ensure an accurate drug history is taken including new or recent onset medications/supplements or illicit substances.
• Ask about thirst and volume loss.
• Check blood pressure, heart rate and urine output.
• Assess for peripheral oedema, ascites and pulmonary oedema.
• Check urinalysis and urinary protein:creatinine ratio.
• If urinalysis positive for blood or protein then:
  • Request GN screen - ANCA, ANA, anti-GBM antibody, rheumatoid factor and C3/C4 complement, and in those aged >60 years a myeloma screen (serum electrophoresis, immunoglobulins and Bence-Jones protein).
  • Check virology  (HCV, HBV, HIV)
• In those aged >60 years with negative urinalysis and AKI, a myeloma screen but not a GN screen should be checked.
• Request renal tract ultrasound to rule out obstruction

Management

• Management of pre-renal AKI focusses on optimisation of fluid balance and cardiovascular support.
• If volume deplete, 5% glucose is not a suitable replacement fluid on its own. If a patient is well-filled and hypotensive, consider inotropes (seek senior advice).
• Hyperkalaemia is a medical emergency and must be treated promptly.
• Close attention should be paid to medication - both existing and prescription of new medication. Medication may need to be temporarily withheld and/or doses may need to be altered. Involve the clinical pharmacist or Medicines Information (see Appendix 6 for contact details).
• For GN, specific treatment may be required - discuss with the renal unit.
• Renal obstruction always needs to be discussed with urology.

If contrast* is necessary for any planned imaging and a patient has an AKI or CKD with an eGFR ≤30ml/minute/1.73m² then the radiologist should be informed and consideration given to the administration of 1 litre of sodium chloride 0.9% in the 12 hours prior to and following the scan. Urgent and essential scans should not be delayed to allow fluid administration. 

*For further information on the use of contrast in patients with renal impairment, see the GGC Constrast Guideline here.

Indications for dialysis include:

• Resistant hyperkalaemia.
• Hyperkalaemia in the setting of oliguria.
• Fluid overload which is unresponsive to diuretics.

Other indications for early discussion with the renal unit include:

• Stage 3 AKI
• Stage 2 AKI that is not resolving after 24/48 hours
• Suspicion of vasculitis
• New nephrotic syndrome
• Glomerulonephritis
• Any transplant or dialysis patient regardless of reason for admission

Other Information

Poisoning as an indication for dialysis:

• Consult TOXBASE (www.toxbase.org, password required) for up to date advice when managing all presentations of poisoning.
• Many drug overdoses are capable of causing AKI, which may necessitate dialysis, however many drugs taken in overdose can be removed via dialysis even in the absence of AKI. 

Guideline reviewed: February 2023

Page last updated: March 2023