The presence of leukocytes, or white blood cells, in the urine may indicate a urinary tract infection, according to the American Association for Clinical Chemistry. Contamination, such as from vaginal secretions, may also cause leukocytes to show up during a urinalysis.
When a urinalysis detects leukocytes, the physician may confirm a urinary tract infection by ordering a urine culture, notes the American Association for Clinical Chemistry. This test identifies the infection-causing bacteria and helps to determine the most effective treatment. In some cases, the physician may order additional testing to see if the infection has spread to the bloodstream. If there is a history of frequent urinary tract infections, a glucose or blood urea nitrogen and creatinine test may be performed as well.