Paeds · nephrology-urology-fluids-and-electrolytes
Acute kidney injury
Also known as Paediatric acute kidney injury · AKI in children · Acute renal failure · ATN in children · Paediatric renal failure
Fellowship guide to paediatric acute kidney injury: the KDIGO definition and three-stage classification using creatinine and urine output criteria, the pre-renal, intrinsic and post-renal framework with acute tubular necrosis the leading intrinsic cause in critically ill children, the staged emergency management of hyperkalaemia and fluid overload, the indications and modality choice for renal replacement therapy, and the long-term risk of chronic kidney disease that now mandates nephrology follow-up after every significant AKI episode.
Checked against its sources on 3 Sept 2026
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Target exams
Red flags
- Hyperkalaemia with ECG changes of peaked T waves, widened QRS, or a sine-wave pattern requiring immediate intravenous calcium gluconate
- Anuria, defined as urine output below 0.1 mL per kg per hour or complete absence for 12 hours or more
- Rapidly rising creatinine with fluid overload, pulmonary oedema, or hypertension suggesting progression to stage 3
- Severe metabolic acidosis with a pH below 7.1 or a bicarbonate below 12 mmol per litre causing myocardial depression
- Uraemic encephalopathy, pericardial rub, or a bleeding diathesis signalling the need for urgent renal replacement therapy
- Post-cardiac-surgery infant with oliguria and a rising creatinine within 48 hours of cardiopulmonary bypass
- Neonate with perinatal asphyxia, low Apgar scores, and oliguria presenting with neonatal AKI
- Child on nephrotoxic agents including aminoglycosides, non-steroidal anti-inflammatory drugs, or contrast with a rising creatinine
Life stages
Care settings
Clinical exam formats
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- Defines acute kidney injury using the KDIGO criteria of creatinine and urine output change over hours to days
- Classifies the cause as pre-renal, intrinsic, or post-renal and recognises the immediately dangerous complications
- Initiates resuscitation, stops nephrotoxic drugs, adjusts doses, and refers to a paediatric nephrologist for severe AKI
- Applies the KDIGO three-stage classification and the paediatric pRIFLE criteria and interprets the fractional excretion of sodium
- Justifies the choice and timing of renal replacement therapy modality for the haemodynamically unstable child
- Counsels on the long-term risk of chronic kidney disease after an AKI episode and arranges nephrology follow-up
- KDIGO definition and staging of acute kidney injury in children
- Immediate resuscitation including the staged management of hyperkalaemia
- Indications for and principles of renal replacement therapy in children
- Recognises a deteriorating child with acute kidney injury and escalates to intensive care and nephrology
- Communicates the gravity of severe AKI and the renal replacement therapy pathway to a family
- Counsels on prognosis including the risk of long-term chronic kidney disease
- Level 1: Recognition of acute kidney injury by creatinine and urine output criteria
- Level 2: Initiation of resuscitation, cause-directed workup, and complication management
- Level 3: Coordination of renal replacement therapy and long-term nephrology follow-up
- KDIGO definition and the three-stage classification of acute kidney injury
- Pre-renal, intrinsic, and post-renal causes and their distinguishing investigations
- Staged management of hyperkalaemia and the indications for renal replacement therapy
- Assessment of fluid status and the clinical signs of hyperkalaemia and fluid overload in a child with AKI
- Interpretation of the fractional excretion of sodium, urinalysis, and the renal ultrasound in AKI
- Structured explanation of the resuscitation, cause-directed treatment, and dialysis pathway
- KDIGO and pRIFLE classification of paediatric acute kidney injury
- Nephrotoxic-medication stewardship and the prevention of hospital-acquired AKI
- Indications, timing, and modality selection for renal replacement therapy in children
- Recognition of acute kidney injury as a time-critical emergency with life-threatening complications
- Initiation of the staged hyperkalaemia protocol and urgent nephrology referral
- Family communication around dialysis, prognosis, and long-term kidney health
- Canadian approach to paediatric acute kidney injury and regional retrieval to renal centres
- Dynamic staging and the move to long-term kidney health surveillance after AKI
- Nephrotoxic-medication stewardship and quality improvement to reduce hospital-acquired AKI
Overview & Definition
A child who was making urine and now is not, whose creatinine is climbing and whose potassium is heading toward a danger zone, has acute kidney injury, one of the most time-critical problems on a paediatric ward or intensive care unit. The defining problem is an abrupt fall in the kidney's ability to filter blood and maintain fluid, electrolyte, and acid-base balance, unfolding over hours to days rather than the months of chronic kidney disease. The danger is immediate and biochemical: potassium rises until the heart stops, acid accumulates until it depresses myocardial function, and fluid accumulates until the lungs drown. [1]
The international standard definition is the KDIGO criteria, published in 2012 and summarised by Kellum and Lameire. Acute kidney injury is present when the serum creatinine rises by 0.3 mg per dL or more within 48 hours, or rises to 1.5 times the baseline value or more within seven days, or when the urine output falls below 0.5 mL per kg per hour for six hours. The threshold matters because it is low enough to catch injury early, before the creatinine has doubled and before the complications become irreversible, and because it gives every clinician a single, reproducible standard rather than a subjective judgement of "renal impairment." [1]
The emergency is two-sided. The failing kidney stops clearing potassium, acid, and fluid, so the child develops biochemical and volume problems that can kill within hours. At the same time the cause may be reversible, which is why resuscitation must run in parallel with a hunt for the cause and an early call to paediatric nephrology and intensive care. A child with volume-responsive pre-renal injury can recover within hours of a fluid bolus, while a child with established acute tubular necrosis needs days to weeks of support and a careful watch for the complications that determine survival. [5]
References13ShowHide
- [1]Kellum JA, Lameire N Diagnosis, evaluation, and management of acute kidney injury: a KDIGO summary (Part 1). Crit Care, 2013.PMID 23394211
- [2]Lameire N, Kellum JA Contrast-induced acute kidney injury and renal support for acute kidney injury: a KDIGO summary (Part 2). Crit Care, 2013.PMID 23394215
- [3]Akcan-Arikan A, Zappitelli M, Loftis LL, Washburn KK, Jefferson LS, Goldstein SL Modified RIFLE criteria in critically ill children with acute kidney injury. Kidney Int, 2007.PMID 17396113
- [4]Kaddourah A, Basu RK, Bagshaw SM, et al. Epidemiology of Acute Kidney Injury in Critically Ill Children and Young Adults. N Engl J Med, 2017.PMID 27959707
- [5]Sutherland SM, Alobaidi R, Gorga SM, et al. Epidemiology of acute kidney injury in children: a report from the 26th Acute Disease Quality Initiative (ADQI) consensus conference. Pediatr Nephrol, 2024.PMID 37874357
- [6]Fitzgerald JC, Basu RK, Fuhrman DY, et al. Renal Dysfunction Criteria in Critically Ill Children: The PODIUM Consensus Conference. Pediatrics, 2022.PMID 34970682
- [7]Basu RK, Zappitelli M, Brunner L, Wang Y, Wong HR, Chawla LS, Goldstein SL Derivation and validation of the renal angina index to improve the prediction of acute kidney injury in critically ill children. Kidney Int, 2014.PMID 24048379
- [8]Moffett BS, Goldstein SL Acute kidney injury and increasing nephrotoxic-medication exposure in noncritically-ill children. Clin J Am Soc Nephrol, 2011.PMID 21212419
- [9]Gist KM, Selewski DT, Brinton J, Menon S, Goldstein SL Assessment of the Independent and Synergistic Effects of Fluid Overload and Acute Kidney Injury on Outcomes of Critically Ill Children. Pediatr Crit Care Med, 2020.PMID 31568240
- [10]Balamuth F, Weiss SL, Long E, et al. Balanced Fluid or 0.9% Saline in Children Treated for Septic Shock. N Engl J Med, 2026.PMID 42028918
- [11]Rutledge AD, Griffin RL, Vincent K, Askenazi DJ, Segar JL Incidence, Risk Factors, and Outcomes Associated With Recurrent Neonatal Acute Kidney Injury in the AWAKEN Study. JAMA Netw Open, 2024.PMID 38329754
- [12]Meena J, Ali S, Robinson C, et al. Late Outcomes Following Acute Kidney Injury in Children: A Systematic Review and Meta-Analysis. JAMA Pediatr, 2026.PMID 42081220
- [13]Geldermann N, Dzimiera J, Fischer H, et al. Acute hyperkalaemia in emergency care: evidence-based approaches Emerg Med J, 2026.PMID 41506858