Acute pyelonephritis

Last reviewed: 6 Jan 2023
Last updated: 12 Jan 2023



History and exam

Key diagnostic factors

  • flank pain
  • costovertebral angle tenderness
  • fever
  • new or different myalgia, or flu-like symptoms
  • presence of risk factors
  • nausea
  • vomiting
Full details

Other diagnostic factors

  • suprapubic tenderness
  • tachycardia
  • hypotension
Full details

Risk factors

  • urinary tract infection
  • diabetes mellitus
  • stress incontinence
  • foreign body in urinary tract (e.g., calculus, catheter)
  • anatomical/functional urinary abnormality
  • immunosuppressive state (e.g., HIV, transplantation, chemotherapy, corticosteroid use)
  • pregnancy
  • frequent sexual intercourse
  • mother with urinary tract infection history
  • new sex partner
  • spermicide use
  • age between 18 and 50 years
  • age >60 years
Full details

Diagnostic investigations

1st investigations to order

  • urinalysis
  • urine culture and sensitivity
  • full blood count
  • erythrocyte sedimentation rate
  • C-reactive protein
  • urea and electrolytes
  • creatinine
  • blood culture (in hospital)
Full details

Investigations to consider

  • renal ultrasound
  • contrast-enhanced CT
  • MRI
Full details

Treatment algorithm


uncomplicated: non-pregnant

complicated: non-pregnant



Expert advisers

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

Consultant Renal Physician

Honorary Associate Professor

Nephrology Department

Leeds Teaching Hospitals NHS Trust

Head of MBChB

School of Medicine

University of Leeds




AL has been the principal applicant/co-applicant for a number of grants including: Engineering and Physical Sciences Research Council Research - Multiplexed AKI biomarker detection with a single molecule biosensor; Leeds Cares - A novel, non-invasive diagnostic approach to assess kidney transplant health through the targeted measurement of biomarkers of kidney injury and immune response in kidney transplant recipients at the Leeds Teaching Hospitals NHS Trust; Kidney Research Yorkshire - Use of enhanced technology to characterise haemodialysis treatment for acute kidney injury (AKI); Bringing It Home - Validation of a micro-sampling technique for measuring tacrolimus and creatinine remotely; and to fund a research nurse; British Renal Society - Renal function assessment with point of care creatinine in diverse populations (RAPID), and several NIHR grants including on a) Improving the quality of post-discharge care following AKI b) An investigation into the use of remote blood sample collection to reduce health inequalities in patients with mental health disorders c) A comparison of remote blood collection devices: a human factor use study d) Defining the characteristics for a novel automatic device to monitor urine output in catheterized patients e) Leeds Medtech and In-vitro Diagnostic Cooperative Grant Extension f) Surgical MedTech Co-operative for the 2019/20 proof-of-principle funding stream g) A pilot investigation into the use of beta-trace protein for residual renal function estimation in haemodialysis h) Application of functional MRI to improve assessment of chronic kidney disease (AFiRM study) i) SuperResPath-Renal: Quantitative super-resolution technology for a fast, decentralised clinical diagnosis of renal pathologies. AL is the co-author of a number of manuscripts including on extracorporeal treatments, AKI, kidney function testing prior to contrast-enhanced CT, plasma exchange and glucocorticoids in severe ANCA-associated vasculitis, COVID-19 rapid diagnostics, multimodal image-guided ablation on management of renal cancer in Von-Hippel-Lindau syndrome, and on a summary of NICE guidance on CKD. AL is the author of several book chapters on nephrology and AKI. AL has received expenses for accommodation and travel for conferences at which he has given lectures, other than those delivered virtually. AL was a member of the AKI Scientific Program Committee for the ISN World Congress of Nephrology 2020-2021 and Chair of this same committee in 2021-2022.


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

Lynda A. Frassetto, MD

Professor of Medicine

Division of Nephrology

University of California

San Francisco


LAF declares that she has no competing interests.

Peer reviewers

Shruti Goel, MBBS, FRCP

Consultant Nephrologist

The Hillingdon Hospital NHS Foundation Trust




SG declares that she has no competing interests.


Tessa Davis

Section Editor, BMJ Best Practice

Consultant in Paediatric Emergency Medicine

Royal London Hospital




TD declares that she has no competing interests.

Emma Quigley

Section Editor, BMJ Best Practice


EQ declares that she has no competing interests.

Susan Mayor

Lead Section Editor, BMJ Best Practice


SM works as a freelance medical journalist and editor, video editorial director and presenter, and communications trainer. In this capacity, she has been paid, and continues to be paid, by a wide range of organisations for providing these skills on a professional basis. These include: NHS organisations, including the National Institute for Health and Care Excellence, NHS Choices, NHS Kidney Care, and others; publishers and medical education companies, including the BMJ Group, the Lancet group, Medscape, and others; professional organisations, including the British Thoracic Oncology Group, the European Society for Medical Oncology, the National Confidential Enquiry into Patient Outcome and Death, and others; charities and patients’ organisations, including the Roy Castle Lung Cancer Foundation and others; pharmaceutical companies, including Bayer, Boehringer Ingelheim, Novartis, and others; and communications agencies, including Publicis, Red Healthcare and others. She has no stock options or shares in any pharmaceutical or healthcare companies; however, she invests in a personal pension, which may invest in these types of companies. She is managing director of Susan Mayor Limited, the company name under which she provides medical writing and communications services.

Rachel Wheeler

Lead Section Editor, BMJ Best Practice


RW declares that she has no competing interests.

Annabel Sidwell

Comorbidities Editor, BMJ Best Practice


AS 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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