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EM TopicsAcute kidney injury

EM · Acute kidney injury

Acute kidney injury

Also known as AKI · Acute renal failure · Pre-renal uraemia · Acute tubular necrosis

Acute kidney injury in the emergency department — KDIGO definition and staging, causes and urinary indices, isotonic fluids and balanced crystalloids, diuretics and contrast, hyperkalaemia, RRT timing and urgent indications, and rhabdomyolysis.

medium25 referencesUpdated 26 July 20265 min readSource-verified · Oct 2026

Checked against its sources on 24 Oct 2026

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Practise this topic8 MCQs with explanations

Target exams

ACEMFRCEMABEMFRCPCCCFPEMEBEEM

Red flags

  • Life-threatening fluid, electrolyte or acid-base changes require emergent RRT
  • Hyperkalaemia with ECG changes requires immediate intravenous calcium
  • Oliguria below 0.5 mL/kg/h for at least six hours meets the AKI definition even before a creatinine threshold is reached
  • KDIGO suggests not using diuretics to treat AKI except for volume overload
On this page

Related topics

  • Fluid resuscitation in the emergency department
  • Electrolyte emergencies — potassium and sodium
  • Sepsis and septic shock — the emergency department approach
  • Renal colic and nephrolithiasis
  • DKA, HHS and hypoglycaemia
  • Adrenal crisis (Addisonian crisis)
Study tools

Your progress

Saved on this device.

Practise this topic8 MCQs with explanations

Target exams

ACEMFRCEMABEMFRCPCCCFPEMEBEEM

Red flags

  • Life-threatening fluid, electrolyte or acid-base changes require emergent RRT
  • Hyperkalaemia with ECG changes requires immediate intravenous calcium
  • Oliguria below 0.5 mL/kg/h for at least six hours meets the AKI definition even before a creatinine threshold is reached
  • KDIGO suggests not using diuretics to treat AKI except for volume overload
The one-line answer

Acute kidney injury is defined by a rapid creatinine rise, reduced urine output, or both. It is a collection of syndromes rather than a single disease; find the cause, use isotonic fluids where indicated, and start renal replacement therapy emergently for life-threatening fluid, electrolyte or acid-base changes.[1][25]

Meet the patient

A 72-year-old man with sepsis has produced almost no urine for eight hours. His creatinine has risen from a baseline of 95 to 340 micromol/L, and his potassium is 6.7 mmol/L.[25]

This is severe AKI with an immediate threat. Creatinine above three times baseline is KDIGO stage 3, and oliguria below 0.5 mL/kg/h for at least six hours meets the urine-output definition of AKI. Life-threatening electrolyte and acid-base changes require emergent RRT.[25]

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References25ShowHide
  1. [1]Ronco C, Bellomo R, Kellum JA. Acute kidney injury Lancet, 2019.PMID 31777389
  2. [2]Lameire N, Van Biesen W, Vanholder R. Acute renal failure Lancet, 2005.PMID 15680458
  3. [3]Susantitaphong P, Cruz DN, Cerda J, et al. World incidence of AKI: a meta-analysis Clin J Am Soc Nephrol, 2013.PMID 23744003
  4. [4]Hoste EA, Bagshaw SM, Bellomo R, et al. Epidemiology of acute kidney injury in critically ill patients: the multinational AKI-EPI study Intensive Care Med, 2015.PMID 26162677
  5. [5]Macedo E, Mehta RL. Timing of dialysis initiation in acute kidney injury and acute-on-chronic renal failure Semin Dial, 2013.PMID 24016050
  6. [6]O'Connor ME, Prowle JR. Fluid Overload Crit Care Clin, 2015.PMID 26410146
  7. [7]Kellum JA, Lameire N; KDIGO AKI Guideline Work Group. Diagnosis, evaluation, and management of acute kidney injury: a KDIGO summary (Part 1) Crit Care, 2013.PMID 23394211
  8. [8]Gaudry S, Hajage D, Schortgen F, et al. Initiation Strategies for Renal-Replacement Therapy in the Intensive Care Unit N Engl J Med, 2016.PMID 27181456
  9. [9]Bagshaw SM, Wald R, Adhikari NKJ, et al. Timing of Initiation of Renal-Replacement Therapy in Acute Kidney Injury N Engl J Med, 2020.PMID 32668114
  10. [10]Zarbock A, Kellum JA, Schmidt C, et al. Effect of Early vs Delayed Initiation of Renal Replacement Therapy on Mortality in Critically Ill Patients With Acute Kidney Injury: The ELAIN Randomized Clinical Trial JAMA, 2016.PMID 27209269
  11. [11]Semler MW, Self WH, Wanderer JP, et al. Balanced Crystalloids versus Saline in Critically Ill Adults N Engl J Med, 2018.PMID 29485925
  12. [12]Self WH, Semler MW, Wanderer JP, et al. Balanced Crystalloids versus Saline in Noncritically Ill Adults N Engl J Med, 2018.PMID 29485926
  13. [13]Carvounis CP, Nisar S, Guro-Razuman S. Significance of the fractional excretion of urea in the differential diagnosis of acute renal failure Kidney Int, 2002.PMID 12427149
  14. [14]Weisbord SD, Gallagher M, Jneid H, et al. Outcomes after Angiography with Sodium Bicarbonate and Acetylcysteine N Engl J Med, 2018.PMID 29130810
  15. [15]Gaudry S, Hajage D, Martin-Lefevre L, et al. Comparison of two delayed strategies for renal replacement therapy initiation for severe acute kidney injury (AKIKI 2): a multicentre, open-label, randomised, controlled trial Lancet, 2021.PMID 33812488
  16. [16]Matuszkiewicz-Rowińska J, Małyszko J Acute kidney injury, its definition, and treatment in adults: guidelines and reality Pol Arch Intern Med, 2020.PMID 32426960
  17. [17]Geldermann N, Dzimiera J, Fischer H, et al. Acute hyperkalaemia in emergency care: evidence-based approaches Emerg Med J, 2026.PMID 41506858
  18. [18]Maxwell AP, Linden K, O'Donnell S, et al. Management of hyperkalaemia J R Coll Physicians Edinb, 2013.PMID 24087806
  19. [19]Ho KM, Sheridan DJ. Meta-analysis of frusemide to prevent or treat acute renal failure BMJ, 2006.PMID 16861256
  20. [20]Allon M, Copkney C. Albuterol and insulin for treatment of hyperkalemia in hemodialysis patients Kidney Int, 1990.PMID 2266671
  21. [21]Allon M, Dunlay R, Copkney C. Nebulized albuterol for acute hyperkalemia in patients on hemodialysis Ann Intern Med, 1989.PMID 2919849
  22. [22]Dombre V, De Seigneux S, Schiffer E. [Sodium chloride 0.9%: nephrotoxic crystalloid?]. Rev Med Suisse, 2016.PMID 26999998
  23. [23]Lindner G, Burdmann EA, Clase CM, et al. Acute hyperkalemia in the emergency department: a summary from a Kidney Disease: Improving Global Outcomes conference. European journal of emergency medicine : official journal of the European Society for Emergency Medicine, 2020.PMID 32852924
  24. [24]Cabral BMI, Edding SN, Portocarrero JP, et al. Rhabdomyolysis. Disease-a-month : DM, 2020.PMID 32532456
  25. [25]Kidney Disease: Improving Global Outcomes (KDIGO) KDIGO 2012 Clinical Practice Guideline for Acute Kidney Injury KDIGO, 2012.Source

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Related topics

  • Fluid resuscitation in the emergency department
  • Electrolyte emergencies — potassium and sodium
  • Sepsis and septic shock — the emergency department approach
  • Renal colic and nephrolithiasis
  • DKA, HHS and hypoglycaemia
  • Adrenal crisis (Addisonian crisis)