Which dipstick parameter is used to detect leukocyte esterase in urine?

• A. Nitrite
• B. Glucose
• C. Leukocyte esterase
• D. Protein

Answer: (C)

Leukocyte esterase on a urine dipstick is the test that detects this enzyme released by neutrophils in the presence of inflammation or infection in the urinary tract. When white blood cells are present in the urine (pyuria), they release leukocyte esterase, and the dipstick reaction is positive. This makes it a direct marker for leukocytes in urine, i.e., a sign of possible a urinary tract infection. The other dipstick parameters measure different things—nitrite indicates bacterial conversion of nitrates, glucose shows glycosuria, and protein reflects proteinuria—so they do not specifically detect leukocyte esterase.