What does the leukocyte esterase test primarily measure?

The leukocyte esterase test primarily measures the presence of white blood cells (WBCs) in the urine. The enzyme leukocyte esterase is released by activated white blood cells, particularly neutrophils, during an immune response to infections. When WBCs are present in urine, their activity leads to the release of this enzyme, which can be detected using specific chemical tests. A positive leukocyte esterase result is often an indicator of a urinary tract infection or other inflammatory conditions in the urinary system.

This test is valuable in clinical settings because it provides a quick and non-invasive method to check for possible infections, prompting further investigation if necessary. Testing for the presence of glucose, bacteria, or ketones involves different methodologies and indicators, making leukocyte esterase a unique and specific test for white blood cell activity.