KIDNEY INFECTION OVERVIEW
A kidney infection, also known as pyelonephritis, is a urinary tract infection that affects the kidneys. Kidney infections are less common than bladder infections, and are more common in women than men.
Kidney infections can usually be treated at home with antibiotics, but are sometimes treated in the hospital if the infection is severe.
This article will review the causes, symptoms, and treatment of kidney infections. An article about bladder infections is available separately. (See "Patient information: Urinary tract infections in adolescents and adults (Beyond the Basics)".)
More detailed information about kidney infections is available by subscription. (See "Acute uncomplicated cystitis and pyelonephritis in women".)
KIDNEY INFECTION CAUSES
Most kidney infections occur when bacteria, which normally live in the gut and travel to the genital area and from there into the bladder through the urethra. From the bladder, the bacteria travel up the ureter(s) into the kidney(s) (figure 1). You can have a kidney infection in one or both kidneys.
Factors that increase the risk of developing a kidney infection include:
- Having sex frequently or having a new sex partner
- Having diabetes
- Having a bladder or kidney infection in the past 12 months
- Using a spermicide for birth control or prevention of infection
- Having a condition that blocks or changes the flow of urine in the kidneys (eg, kidney stones, ureteral reflux)
KIDNEY INFECTION SYMPTOMS
Symptoms of a kidney infection include:
- Fever (temperature greater than 100.4º F or 38º C)
- Pain in the flank (side of lower back, where the kidney is located)
- Nausea and/or vomiting
Some people also have burning or pain with urination, a need to rush to the bathroom frequently, bloody or cloudy urine, or pain above the pubic bone (near the bladder).
If you do not have a fever or flank pain, but you do have pain with urination, you may have a bladder infection rather than a kidney infection. Your healthcare provider can help to determine your diagnosis. (See "Patient information: Urinary tract infections in adolescents and adults (Beyond the Basics)".)
If you have one or more of these symptoms, you should see a healthcare provider as soon as possible. Although most kidney infections do not cause permanent damage, delaying treatment can lead to serious complications.
KIDNEY INFECTION DIAGNOSIS
Kidney infections are usually diagnosed based upon your symptoms, a physical examination, and urine testing. X-rays and other imaging tests are not usually needed.
KIDNEY INFECTION TREATMENT
The optimal treatment for a kidney infection depends upon the severity of your infection and your general health. (See "Acute uncomplicated cystitis and pyelonephritis in women".)
Home treatment — If your fever and pain are mild and you are able to eat and drink, you will probably be given a one to two week course of antibiotics to take by mouth at home. The first dose of antibiotics may be given as an injection in the office, clinic, or emergency department. Let your healthcare provider know if you do not begin to feel better within one to two days after starting treatment.
For fever and pain, you can take a non-prescription medication like acetaminophen (eg, Tylenol® and others) or ibuprofen (Motrin®, Advil®).
Hospital treatment — If you have a high fever, severe pain, or cannot keep down food/fluids, you will need to be hospitalized and given intravenous (IV) antibiotics and fluids. As you begin to improve, you will be switched to oral antibiotics and allowed to go home and continue taking antibiotics there.
Most pregnant women with a kidney infection are hospitalized and treated with intravenous (IV) antibiotics and fluids. (See "Urinary tract infections and asymptomatic bacteriuria in pregnancy".)
Recovery — Most people recover from a kidney infection within a few days. Some people need to take time off from work or school, although this is not always necessary.
Prevention — Ways to prevent bladder and kidney infections are discussed separately. (See "Patient information: Urinary tract infections in adolescents and adults (Beyond the Basics)", section on 'Preventing recurrent UTIs'.)
WHERE TO GET MORE INFORMATION
Your healthcare provider is the best source of information for questions and concerns related to your medical problem.
This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.
Patient level information — UpToDate offers two types of patient education materials.
The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.
Patient information: Prenatal hydronephrosis (The Basics)
Patient information: Diabetes and infections (The Basics)
Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.
Patient information: Urinary tract infections in adolescents and adults (Beyond the Basics)
Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.
Bacterial adherence and other virulence factors for urinary tract infection
Treatment of enterococcal infections
Urinary tract infections and asymptomatic bacteriuria in pregnancy
Acute uncomplicated cystitis and pyelonephritis in women
The following organizations also provide reliable health information.
- National Library of Medicine
(http://www.nlm.nih.gov/medlineplus/ency/article/000521.htm, available in Spanish)
- National Institute of Diabetes and Digestive and Kidney Diseases