Which tests should be performed in the diagnosis of pyuria in men?

Updated: Jan 02, 2020
  • Author: John L Brusch, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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The most accurate method to measure pyuria is counting leukocytes in unspun fresh urine using a hemocytometer chamber; more than 10 WBCs/mL is considered abnormal. Examination for pyuria is a sensitive (80-95%), but nonspecific (50-76%), method of diagnosing UTI. WBC counts determined from a wet mount of centrifuged urine are not reliable measures of pyuria. An uncontaminated specimen is suggested by a lack of squamous epithelial cells.

White cell casts in urine specimens may be observed in conditions other than infection, and they may not be observed in all cases of pyelonephritis. If the patient has evidence of acute infection and white cell casts are present, the infection likely represents pyelonephritis. A spun sample (5mL at 2000rpm for 5min) is best used for evaluation of cellular casts.

The presence of leukocyte esterase on a dipstick test is a rapid screening for pyuria; it is 57-96% sensitive and 94-98% specific for identifying pyuria.

The nitrite test is a rapid screening test for bacteriuria; false-negative test results are seen in low-grade bacteriuria, but false-positive results are rare. A positive nitrite test has 27% sensitivity and 94% specificity for UTI when the cutoff is 100,000 CFU/mL.

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