Leukocyte esterase urine test
WBC esteraseLeukocyte esterase is a urine test to look for white blood cells and other signs of infection.
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How the Test is Performed
A clean-catch urine sample is preferred. The clean-catch method is used to prevent germs from the penis or vagina from getting into a urine sample. To collect your urine, the health care provider may give you a special clean-catch kit that contains a cleansing solution and sterile wipes. Follow instructions exactly so that the results are accurate.
After you provide a urine sample, it is tested right away. The provider uses a dipstick made with a color-sensitive pad. The color of the dipstick changes to tell the provider if you have white blood cells in your urine.
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How to Prepare for the Test
No special steps are needed to prepare for this test.
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How the Test will Feel
The test will involve only normal urination. There is no discomfort.
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Why the Test is Performed
Leukocyte esterase is a screening test used to detect a substance that suggests there are white blood cells in the urine. This may mean you have a urinary tract infection.
If this test is positive, the urine should be examined under a microscope for white blood cells and other signs that point to an infection.
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Normal Results
A negative test result is normal.
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What Abnormal Results Mean
An abnormal result indicates a possible urinary tract infection.
The following may cause an abnormal test result, even when you do not have a urinary tract infection:
- Trichomonas infection (such as trichomoniasis)
- Vaginal secretions (such as blood or heavy mucus discharge)
The following may interfere with a positive result, even when you do have a urinary tract infection:
- High level of protein
- High level of vitamin C
References
Castle EP, Wolter CE, Woods ME. Evaluation of the urologic patient: testing and imaging. In: Partin AW, Dmochowski RR, Kavoussi LR, Peters CA, eds. Campbell-Walsh-Wein Urology. 12th ed. Philadelphia, PA: Elsevier; 2021:chap 2.
Riley RS, McPherson RA. Basic examination of urine. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 29.
Sobel JD, Brown P. Urinary tract infections. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 72.