Why is leukocyte esterase testing important in a urine dipstick?

• A. It measures creatinine clearance
• B. It detects leukocytes indicating pyuria and possible urinary tract infection or inflammation
• C. It measures urine pH
• D. It detects bacteria directly

Answer: (B)

Leukocyte esterase testing on a urine dipstick is a marker for white blood cells in the urine, known as pyuria. When the urinary tract is inflamed or infected, neutrophils migrate into the urine and release leukocyte esterase. The dipstick detects this enzyme, producing a color change that signals that white blood cells are present and an inflammatory or infectious process may be occurring. This quick result helps screen for a urinary tract infection or other inflammation without needing immediate culture results. It won’t measure creatinine clearance, nor does it assess urine pH, and it doesn’t detect bacteria directly—bacteria are inferred indirectly through the presence of white cells.