A false positive result may occur in the presence of strong oxidizing agents in the collection container. In random urine specimens from women, a positive result for leukocyte esterase may be due to a source external to the urinary tract.

Other urine sediment findings such as bacteria, squamous or renal epithelial cells, lymphocytes or red blood cells do not contain esterases, and would not produce a positive leukocyte esterase test.