Definition
Acute kidney injury (AKI) is defined as an abrupt (within hours) decrease in kidney function which encompasses both injury (structural damage) and impairment (loss of function).
Criteria
Kidney Disease Improving Global Outcomes (KDIGO) Group
Stage 1
- Increase in serum creatinine by >26.5µmol/L
- Increase in serum creatinine 1.5-1.9 × baseline
- Urine output <0.5ml/kg/hr for 6 hours
Stage 2
- Increase in serum creatinine 2-2.9 × baseline
- Urine output <0.5ml/kg/hr for 12 hours
Stage 3
- Increase in serum creatinine 3 × baseline
- OR Increase in serum creatinine to >350µmol/L
- OR initiation of RRT
- Urine output <0.3ml/kg/hr for ≥24 hours or anuria for ≥12 hours
Some risk factors for AKI
- Chronic kidney disease
- Diabetes
- Older age
- Liver disease
- Previous AKI
- Nephrotoxic drugs
- Sepsis
Other causes to consider
- Rhabdomyolysis
- HUS
- Tumour lysis syndrome
- Glomerulonephritis
- Interstitial nephritis
- Drugs e.g. PPI
- Sarcoidosos
Examination
All patients must have a urine dipstick with results documented
Urine PCR if presence of proteinuria
Fluid status, BP, JVP, loin tenderness, palpable bladder, rash, oedema, signs of autoimmune disease
Review the drug chart!
Specific renal investigations
Patients with AKI require the following blood test at least once a day until recovering renal function: U+E, venous bicarbonate, bone profile
Other tests to consider:
- Autoimmune screen to be sent in suspected cases of vasculitis or glomerulonephritis :
- ANCA, ANA, dsDNA
- Anti -GBM
- Rheumatoid factor
- Complement
- Myeloma screen should be considered, when appropriate, with the following sent :
- Serum electrophoresis
- Immunoglobulins and Bence Jones proteins
- Renal ultrasound – if appropriate, if possible compare with previous imaging