Leukocyte esterase is a urine test to look for white blood cells and other signs of infection.
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.
How to Prepare for the Test
No special steps are needed to prepare for this test.
How the Test will Feel
The test will involve only normal urination. There is no discomfort.
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.
A negative test result is normal.
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean
An abnormal result indicates a possible urinary tract infection.
The following may turn the test abnormal even when you do not have a urinary infection:
- Trichomonas infection (such as trichomoniasis)
- Vaginal secretions (such as blood or heavy mucus discharge)
The following may turn the test even when you do have an urinary infection:
- High level of protein
- High level of vitamin C
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Riley RS, McPherson RA. Basic examination of urine. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 28.
Sobel JD, Kaye D. Urinary tract infections. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 74.