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Kidney Infection

(Infection, Kidney; Pyelonephritis)
  • Definition

    Kidney infections may occur in one or both kidneys.
    The kidneys remove waste from the body through urine. They also balance the water and mineral content in the blood. An infection may prevent them from working properly.
    Anatomy of the Kidney
    Copyright © Nucleus Medical Media, Inc.
  • Causes

    Kidney infections are caused by a bacteria. The specific type of bacteria can vary. The bacteria most often comes from an untreated bladder infection .
  • Risk Factors

    Bacteria may be introduced to the urinary tract and ultimately the kidneys by:
    • Sexual activity
    • Conditions that block or slow the flow of urine such as:
      • Tumors
      • Enlarged prostate gland
      • Kidney stones
      • Birth defect of the urinary tract, including vesicoureteral reflux
    • Having a test to examine the bladder— cystoscopy
    • Catheter or stent placed in the urinary tract
    • Conditions that impair bladder emptying like multiple sclerosis and spina bifida
    Other medical conditions that increase your risk of infection include:
  • Symptoms

    Symptoms of kidney infection may include:
    • Pain in the abdomen, lower back, side, or groin
    • Frequent urination
    • Urgent urination that produces only a small amount of urine
    • Sensation of a full bladder—even after urination
    • Burning pain with urination
    • Fever and chills
    • Nausea and vomiting
    • Pus and blood in the urine
    • Loss of appetite
  • Diagnosis

    Your doctor will ask about your symptoms and medical history. A physical exam will be done. A kidney infection is diagnosed with urine tests . The urine is examined for:
    • Bacteria or other signs of infection
    • Blood
    • Protein
    • Other abnormal elements
    You may need further tests if the infection does not go away with treatment or if you have had several infections. These tests will be done to see if there are problems with the kidney, ureters, and bladder. Images of these structures can be taken by:
  • Treatment

    Complications from untreated or poorly treated kidney infection can lead to:
    • A serious infection that spreads throughout the body— sepsis
    • Chronic infection
    • Severe kidney disease, which may result in scarring of tissue or permanent damage
    You will be treated with antibiotics. Be sure to take all of the medication. Antibiotics may need to be delivered through an IV. This may require a stay in the hospital.
  • Prevention

    Surgical correction of vesicoureteral reflux in children may reduce risk for pyelonephritis.
    Since kidney infection is often a complication of a bladder infection. You can prevent bladder infections if you:
    • Drink plenty of fluids throughout the day. Cranberry juice is a good choice to prevent bladder infection.
    • Practice good hygiene.
    • Urinate when you need to.
    • Take showers rather than baths.
    • For women:
      • Wipe from the front to the back after using the toilet.
      • Urinate before and after sex. Drink water to help flush bacteria.
      • Avoid genital deodorant sprays and douches.
    • Circumcision in men is associated with a reduced risk of bladder infection

    National Kidney Foundation

    Urology Care Foundation


    The Kidney Foundation of Canada

    Women's Health Matters


    Complicated urinary tract infection (UTI). EBSCO DynaMed website. Available at: Updated July 1, 2014. Accessed August 13, 2014.

    Pyelonephritis: Kidney infection. National Kidney and Urologic Diseases and Information Clearinghouse website. Available at: Updated June 11, 2012. Accessed August 13, 2014.

    Uncomplicated urinary tract infection (UTI). EBSCO DynaMed website. Available at: Updated April 16, 2014. Accessed August 13, 2014.

    Urinary tract infection (UTI) in men. EBSCO DynaMed website. Available at: Updated June 27, 2014. Accessed August 13, 2014.

    3/6/2013 DynaMed's Systematic Literature Surveillance Nikolaidis P, Casalino DD, Remer EM. American College of Radiology Appropriateness Criteria Acute Pyelonephritis. National Guideline Clearinghouse website. Available at: Updated 2012.

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