Address For Correspondence:
R Bhimma, Department of Paediatrics & Child Health, Nelson R Mandela School of Medicine, University of Kwazulu-Natal, Private Bag 7, Congella, 4013, South Africa.
Email: bhimma@ukzn.ac.za


The lack of a uniform definition of AKI in adults and children has lead to the adoption of a new classification system entitled the RIFLE criteria as a standardize criteria for AKI in adults [16] and has been adapted for paediatric patients [17]. The paediatric RIFLE (p-RIFLE) classification better reflects the course of AKI in children admitted to the intensive care unit [Table 1]. The new classification system aims to standardize the definition of AKI based on changes in serum creatinine from baseline, a decrease in urine output, as well as the length of renal replacement at later stages. In adults, the RIFLE criteria were shown in a multinational and multicentre study to independently predict length of stay, cost, morbidity, and mortality [18]. However no similar paediatric studies are available. To aid in the differential diagnosis of AKI, in general terms, AKI may be classified as pre-renal, intrinsic renal, and post-renal. However many pathophysiological features are shared among the different categories [Table 2,3,4].

Table 1: Paediatric-modified RIFLE (p-RIFLE) criteria

	Estimated CCI	Urine Output
Risk	eCCI decrease by 25%	< 0.5 ml/kg/h for 8 h
Injury	eCCI decrease by 50%	<0.5 ml/kg/h for 16 h
Failure	eCCI decrease by 75%  eCCI <35ml/min/1.73m2	<0.3 ml/kg/h for 24 h or Anuric for 12 h
Loss	Persistent failure >4weeks
End stage	End-stage renal disease  (persistent failure >3 months)

eCCI estimated creatinine clearance, p-RIFLE pediatric risk, injury, failure, loss and end-range renal disease.

eCCI was calculated using the Schwartz formula. Adapted with permission from [17].

Table 2: Aetiology of common causes of pre-renal acute kidney injury in children

Decreased true intravascular volume Haemorrhage   Dehydration due to gastrointestinal losses   Salt wasting renal or adrenal diseases   Central or nephrogenic diabetes insipidus   Increased insensible losses e.g. burns   In disease status associated with third space losses e.g. sepsis, nephrotic syndrome, traumatized tissue and capillary leak syndrome

Decrease effective intravascular volume Congestive heart failure   Cardiac tamponade   Hepatorenal syndrome

Table 3: Aetiology of common in intrinsic renal disease in children

• Acute renal necrosis (vasomotor nephropathy)
  
        -  Hypoxic / ischemic insults
        -  Drug induced
        -  Toxin mediated
  
  
  • Endogenous toxins- haemoglobin, myoglobin
    
    
  • Exogenous toxins- ethylene glycol, methanol
    
    
 
• Uric nephropathy and tumour lysis syndrome
 
• Interstitial nephritis
  
        -  Drug induced
        -  Idiopathic
  
 
• Glomerulonephritis - Rapid progressive glomerulonephritis
 
• Vascular lesions
  
        -  Renal artery thrombosis
        -  Renal vein thrombosis
        -  Cortical necrosis
        -  Hemolytic artery syndrome
  
 
• Hypoplasia/ dysplasia with or without
  
        -  Obstructive uropathy
        -  Idiopathic
        -  Exposure to nephrotoxic drug in utero

Table 4: Aetiology of common causes of post renal acute kidney injury in children

• Obstruction in solitary kidney
 
• Bilateral ureteral obstruction
 
• Urethral Obstruction