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Medical Author:

Siamak T. Nabili, MD, MPH

Siamak T. Nabili, MD, MPH

Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.

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Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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The most important test in diagnosing kidney infection is a urinalysis (UA). This is basically a test to analyze urine sample and evaluate for an infection in the urine. Urinalysis is done by collecting a clean catch, midstream urine in a sterile collection cup. The urine may be analyzed by the doctor in the office using a urine dipstick or by a formal analysis in a laboratory.

Because urine is normally sterile, any finding suggesting an infection may be considered abnormal and supportive of a kidney infection.

• Gross inspection of urine (macroscopic analysis) may reveal cloudy urine.
  
  
• With a dipstick urine test, typical findings consistent with urinary tract infection include positivity for leukocyte esterase, nitrates, or blood.
  
  
• In microscopic urinalysis (analysis under the microscope), the presence of white blood cells or bacteria in the urine is highly suggestive of a kidney infection. Generally, visualization of 100,000 bacteria in one cc of a urine sample supports the diagnosis of urinary tract infection or kidney infection.
  
  
• In some situations, less than 100,000 bacteria may still be enough to make the diagnosis. If no white blood cells or bacteria are seen in the urine, then another diagnosis may need to be considered.
  
  
• When bacteria are recovered from urine, they need to be further analyzed to determine the exact type of bacteria. Once the exact type of bacteria is known, usually its sensitivity to typical antibiotics is also tested to further guide of treatment.
  
  
• In more complicated cases, imaging studies, such as a CT scan of the abdomen and pelvis, may also be necessary. Complicated kidney infections are usually associated with more severe symptoms and with more significant involvement of the kidneys including an abscess or gas formation in the kidney which can be detected by CT scan.
  
  
• Recurrent or long-standing (chronic) kidney infections sometimes result from kidney stones or other structural abnormalities, such as an enlarged prostate or long-standing reflux of urine in the ureters (vesiculo-ureteral reflux). X-rays, ultrasounds, or CT scans may be necessary to investigate these cases.

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