Signs and Symptoms of Kidney Infection

Kidney infections often cause urinary problems, such as the need to urinate more often, an inability to urinate, blood in the urine (hematuria), and pus in the urine. Infections also can cause changes in urine color or odor.

Other symptoms of kidney infections include the following:

  • Back or abdominal pain
  • Confusion
  • Fatigue
  • Fever, chills, night sweats
  • Loss of appetite
  • Nausea
  • Skin that is warm and/or moist, and reddened

Complications of Kidney Infection

Because the symptoms of kidney infections and other urinary tract infections (UTIs) are similar, kidney infections may be difficult to diagnose. Patients should contact their health care provider at the first sign of symptoms. Early detection and treatment of a UTI can decrease the likelihood that a kidney infection will develop.

It is important to keep the infection from spreading and from entering the bloodstream. Untreated kidney infections can cause blood poisoning, kidney scars, kidney disease, and permanent kidney damage. Kidney infections during pregnancy can result in premature labor and low birth weight.

Kidney Infection Diagnosis

To diagnose a kidney infection, the health care provider reviews the patient's medical history, checking in particular for a history of urinary tract infection (UTI). During physical examination, the physician may gently press the kidney area to see how tender or painful it is. Other symptoms also are considered; for example, fever and back pain are more likely to indicate a kidney infection than a lower urinary tract infection.

Laboratory tests include urine samples to detect blood, pus, bacteria, white blood cells, or red blood cells in the urine. Blood tests may be performed to check for infection.

In some cases, imaging tests (e.g., x-rays, CT scan) are used to check for enlarged kidneys or other problems that may affect kidney function. If an abnormality is detected, ultrasound, kidney scan, and biopsy (removal of a small sample of tissue for microscopic examination) may be performed.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 03 Jun 2007

Last Modified: 22 Sep 2015