Acute Kidney Injury

Previously known as acute renal failure. Usually doesn’t occur in isolation

Stages

Stage	Creatinine	Urine Output
1	SCr increase >26 $\mu$mol/L within 48hr or SCr increase 1.5-1.9x baseline	<0.5mL/kg/hr for 6 hours
2	SCr 2-2.9x increase from baseline	<0.5mL/kg/hr for 12 hours
3	SCr 3x increase etc, SCr increase $\ge$ 354, initiated on RRT	<0.3mL/kg/hr for 24 hrs

Causes/Factors

Lots of risk factors like age 75+, Diabetes Mellitus, Heart Failure, etc

Pre-renal - something causes $\downarrow$ BP

• vomiting
• Diarrhoea
• Diuretics
• Haemorrhage
• Burns
• Renal Artery Stenosis

Intrinsic - something within the kidney

• NSAIDS
• Nephrotoxins
• Glomerulonephritis
• Vascular

Post-renal

• Kidney stones
• Tumours
• Retroperitoneal fibrosis

Clinical Presentation

• AKI is usually a silent disease
• Possibly kidney stones
• Always suspect in acute patients with risk factors

Diagnostic Tests

• FBC, U&E and bicarbonate, C reactive protein (CRP), LFTs
• Calcium & phosphate
• Creatine kinase
• Urinalysis
• Ultrasound if suspected obstruction
• Biopsy

Management

• Manage underlying cause of AKI
• Supportive - renal (kidney) replacement therapy
  • hyperkalaemia - non-responsive to medicine
  • pH <7.1
  • high urea

Complications/red Flags

Refractory Hyperkalaemia

• Leads to tented T-wave
• Give calcium gluconate → protects heart and buys time, glucose/dextrose + Insulin and possible Salbutamol nebuliser

Acidosis

Uraemic symptoms

• nausea
• pruritis
• malaise

Therapy-resistant fluid overload