In urinalysis, leukocyte esterase positivity indicates which of the following?

• A. Hematuria indicates infection.
• B. Proteinuria indicates infection.
• C. Presence of white blood cells in urine indicates UTI
• D. Glucose in urine indicates infection.

Answer: (C)

Leukocyte esterase detects the enzyme released by white blood cells in urine, so a positive result signals pyuria—the presence of white blood cells in the urine. In the setting of urinary symptoms, pyuria most commonly points to a urinary tract infection because neutrophils flood the urinary tract in response to infection. Therefore, seeing leukocyte esterase positivity is most consistent with a UTI, especially when interpreted alongside other findings and the patient’s symptoms. It’s a helpful clue, but not definitive on its own, since other inflammatory conditions can cause white blood cells in urine and false positives or negatives can occur; clinicians often consider nitrite testing and urine culture to confirm infection.

The other listed findings describe different urine abnormalities. Blood in the urine is hematuria, not indicated by leukocyte esterase. Protein in the urine is proteinuria, which is unrelated to leukocyte enzymes. Glucose in the urine is glycosuria, again not related to leukocyte esterase activity.