Acute kidney injury

Last reviewed: 18 Jul 2022
Last updated: 05 Mar 2020



History and exam

Key diagnostic factors

  • hypotension
  • risk factors
  • kidney insults
  • reduced urine production
  • lower urinary tract symptoms
  • symptoms of volume overload/pulmonary oedema
  • vomiting/nausea
  • fever, rash, and/or arthralgia
  • haematuria (visible or non-visible)
  • palpable bladder and/or enlarged prostate and/or abdominal distension
Full details

Other diagnostic factors

  • dizziness and orthostatic symptoms
  • hypertension
  • altered mental status
  • pericardial/pleural rub
  • muscle tenderness
  • haemoptysis
  • abdominal bruit
Full details

Risk factors

  • advanced age
  • underlying kidney disease
  • diabetes mellitus
  • sepsis
  • iodinated contrast
  • exposure to nephrotoxins (e.g., aminoglycosides, vancomycin + piperacillin-tazobactam, cancer therapies, non-steroidal anti-inflammatory drugs, or ACE inhibitors)
  • excessive fluid loss
  • surgery
  • haemorrhage
  • recent vascular intervention
  • cardiac arrest
  • pancreatitis
  • trauma
  • malignant hypertension
  • myeloproliferative disorders, such as multiple myeloma
  • connective tissue disease
  • sodium-retaining states (e.g., congestive heart failure, cirrhosis, nephrotic syndrome)
  • drug overdose
  • nephrolithiasis
  • drug abuse
  • alcohol abuse
  • excessive exercise
  • recent blood transfusion
  • malignancy
  • genetic susceptibility
  • use of renin-angiotensin system inhibitors
  • proton pump inhibitors
  • herbal therapy
Full details

Diagnostic investigations

1st investigations to order

  • basic metabolic profile (including urea and creatinine and liver function tests)
  • serum potassium
  • FBC
  • bicarbonate
  • C-reactive protein
  • blood culture
  • urinalysis
  • urine culture
  • urine output monitoring
  • fluid challenge
  • venous blood gases
  • CXR
  • ECG
Full details

Investigations to consider

  • renal tract ultrasound
  • abdominal CT or MRI scan
  • nuclear renal flow scan
  • urine osmolality
  • urine sodium concentration
  • fractional excretion of sodium/urea
  • urinary eosinophil count
  • serum creatine kinase
  • ANA (anti-nuclear antibodies)
  • anti-dsDNA
  • complement (C3, C4, CH50)
  • anti-glomerular basement membrane antibody
  • anti-neutrophil cytoplasmic antibodies (ANCA)
  • acute hepatitis profile
  • HIV serology
  • cryoglobulins
  • anti-streptolysin-O antibody
  • serum/urine electrophoresis
  • cystoscopy
  • kidney biopsy
Full details

Emerging tests

  • novel serum and urinary biomarkers
Full details

Treatment algorithm





Expert advisers

Andrew Lewington, BSc (Hons), MBBS, MEd, MD, FRCP

Consultant Renal Physician

Honorary Associate Professor

Nephrology Department

Leeds Teaching Hospitals NHS Trust




AL is Associate Clinical Director of NIHR Leeds In-Vitro Diagnostics Co-operative, Co-Chair of UK Kidney Research Consortium Renal Clinical Study Group, Member of Kidney Research UK Research Grant Committee, Committee Member of NICE Kidney Injury Clinical Guideline Update 2018-20, Committee Member of NICE Diagnostic Assessment for Point of Care Creatinine Testing 2018-19. AL attended the Acute Dialysis Quality Initiative Meeting in San Diego 2018 (accommodation expenses); AL was a speaker at the AKI & CRRT Conference in San Diego 2019 (travel and accommodation expenses), the AKI Conference in Coventry 2019 (travel expenses), and the NIHR AKI and Sepsis Meeting in Leeds 2019 (no expenses).


BMJ Best Practice would like to gratefully acknowledge the previous expert contributor, whose work has been retained in parts of the content:

Richard A. Lafayette MD

Professor of Medicine

Nephrology Division

Stanford University Medical Center




RAL works as a consultant and researcher for Relypsa, Inc. Although unrelated to this topic area, RAL also works as a consultant for Fibrogen, Inc.; Mallinckrodt, Inc.; and Omeros, Inc.; and as a researcher for Genentech, Inc.; Mallinckrodt, Inc.; GlaxoSmithKline, Inc.; Rigel, Inc.; Aurinia, Inc.; and the NIH.

Peer reviewers

Suren Kanagasundaram,

Consultant Nephrologist

Newcastle upon Tyne Hospitals NHS Trust

Clinical Lead 

Newcastle Hospitals Haemodialysis Service 

Honorary Clinical Senior Lecturer 

Newcastle University




SK was an expert adviser to the National Confidential Enquiry into Patient Outcome and Death (NCEPOD) report into AKI and is lead author of the UK Renal Association clinical practice guideline on AKI.


Tessa Davis,

Section Editor, BMJ Best Practice

Consultant in Paediatric Emergency Medicine

Royal London Hospital




TD declares that she has no competing interests.

Jo Haynes,

Head of Editorial, BMJ Knowledge Centre


JH declares that she has no competing interests.

Julie Costello,

Comorbidities Editor, BMJ Best Practice


JC declares that she has no competing interests.

Adam Mitchell,

Drug Editor, BMJ Best Practice


AM declares that he has no competing interests.

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