What does a positive leukocyte esterase and nitrite in urinalysis suggest in a patient?

A positive leukocyte esterase and nitrite in urinalysis strongly suggests the presence of a urinary tract infection (UTI). Leukocyte esterase is an enzyme released by white blood cells, indicating that there is an inflammatory response in the urinary tract, typically due to an infection. The presence of nitrites suggests that certain bacteria, particularly Gram-negative bacteria like Escherichia coli, are present in the urine. These bacteria convert urinary nitrates into nitrites, which is a common marker for a UTI.

In the context of the question, the combination of these two findings — leukocyte esterase and nitrites — provides a significant indication of an active infection in the urinary system. Other potential reasons for their presence, like kidney stones or dehydration, do not commonly present with these specific urinalysis markers, reinforcing the diagnosis of a UTI as the most likely condition indicated by the findings.