Usually, the presence of leukocytes (WBCs) in the urine indicates a UTI. The leukocyte esterase test detects esterase released by the leukocytes into the urine. Elevation of leukocyte esterase, a bacteria-related enzyme, is consistent with infection. This is a standardized means for the detection of WBCs.

Microscopic examination and chemical testing are used to determine the presence of leukocytes in the urine. The chemical test is done with a leukocyte esterase dipstick. This test can also detect intact leukocytes, lysed leukocytes, and WBC casts.

Negative for leukocyte esterase

1. Collect a fresh, random urine specimen with a clean-catch or midstream technique.

2. Follow directions for dipstick use exactly. Timing is critical for accurate results.

3. Note that a positive result causes a purple color on the dipstick. The test is not designed to measure the amount of leukocytes.

1. Positive results are clinically significant and may indicate:

   1. Cystitis (UTI)

   2. Acute pyelonephritis

   3. Acute Bright disease

   4. Bladder tumor

   5. SLE

   6. Tuberculosis infection

2. Urine with positive results from the dipstick should be examined microscopically for WBCs and bacteria.

Pretest Patient Care

1. Explain purpose of test, procedure for urine collection, and interfering factors.

2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

1. False-positive results

   1. Vaginal discharge, parasites, histocytes

   2. Drug therapies (e.g., ampicillin, kanamycin)

   3. Salicylate toxicity

   4. Strenuous exercise

2. False-negative results

   1. Large amounts of glucose or protein

   2. High SG

   3. Certain drugs (e.g., tetracycline)