Loading icon
Press enter or spacebar to select a desired language.
Health Information Center

Acute Kidney Injury

  • Amy Scholten, MPH
Publication Type:


Acute Kidney Injury

(AKI; Acute Kidney Failure; Acute Renal Failure; Acute Renal Insufficiency)


Acute kidney injury (AKI) is the sudden loss of kidney function. Kidneys clean waste products from the blood and get rid of extra fluids in the body. Problems can happen:

  • Before blood enters the kidneys
  • Inside the kidneys (most common)
  • When urine leaves the kidneys and moves toward the bladder
Anatomy of the Kidney.

Glomerulonephritishttp://services.epnet.com/getimage.aspx?imageiid=81388138Glomerulonephritis_New.jpgGlomerulonephritisNULLjpgGlomerulonephritisNULL\\hgfiler1\intellect\images\Glomerulonephritis_New.jpgNULL72NULL2010-10-113064268138_234981Copyright © Nucleus Medical Media, Inc.


AKI has many causes:

  • Blood is reduced or blocked from going into the kidneys because of:
  • Problems inside the kidney cause damage to the filters because of:
    • Problems after surgery
    • Inflammation
    • Medicine side effects
  • Problems that can block urine flow such as:

Risk Factors

AKI is most common in older adults. Other things that raise the risk are:

  • Long term diseases, such as:
  • Dehydration
  • Infection
  • Bleeding from the stomach or intestines
  • Certain medicines and illegal drugs
  • Problems during or after surgery or a hospital stay
  • Blockages, which can happen with benign prostatic hyperplasia or a bladder tumor


Most people do not have symptoms. In those that have them, AKI may cause:

  • Changes in urination (peeing), such as:
    • Lower or higher amounts of urine than normal
    • Dark or red urine
  • Tiredness
  • Confusion
  • Nausea or vomiting
  • Muscle weakness or cramps
  • Lack of hunger
  • Swelling
  • Weight gain


The doctor will ask about symptoms and past health. Blood and urine tests will be done to measure levels of toxins and proteins. It will show how well the kidneys are working. Images of the kidneys may be taken with:


Care depends on the cause of AKI and how serious it is. The goal is to manage the cause and support the kidneys until they can work again. The kidneys may be able to recover normal function once they have had a chance to rest. Care may involve:

  • Stopping or changing medicines causing harm to the kidneys
  • Controlling blood pressure and diabetes
  • Avoiding medicine that could be harmful
  • Limiting salt and protein in the diet
  • IV fluids
  • Dialysis—a machine that filters blood while the kidneys are not working
  • Caring for problems such as kidney stones or infections

Some AKIs can cause lasting severe damage to kidneys. Long term dialysis or a kidney transplant may be needed.


Most AKI cannot be prevented. Treatments and testing may be adjusted in certain high risk situations. This may help lower the risk.





  • Acute kidney injury. EBSCO DynaMed website. Available at: https://www.dynamed.com/approach-to/acute-kidney-injury-approach-to-the-patient.
  • Acute kidney injury (AKI). Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/genitourinary-disorders/acute-kidney-injury/acute-kidney-injury-aki.
  • Kidney failure. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: https://www.niddk.nih.gov/health-information/kidney-disease/kidney-failure.
  • Levey AS, James MT. Acute kidney injury. Ann Intern Med. 2017;167(9):ITC66-ITC80.


  • Daniel Ostrovsky, MD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.