Which finding can indicate a urinary tract infection in a urinalysis?

The presence of nitrates in a urinalysis is a significant indicator of a urinary tract infection (UTI). This is based on the fact that certain bacteria, particularly those from the Enterobacteriaceae family like E. coli, have the ability to reduce urinary nitrates to nitrites. When these bacteria are present in the urine, nitrites can be detected, serving as a clear marker for the potential presence of an infection.

Low specific gravity, while it may suggest a variety of conditions such as overhydration or certain renal issues, is not a specific indicator of a urinary tract infection. Similarly, high pH levels can occur with various forms of urinary manipulations or conditions such as a UTI caused by urea-splitting organisms, but it is not exclusively indicative of an infection. The presence of epithelial cells in the urine may reflect contamination or other benign conditions rather than an infection. Therefore, the specific detection of nitrates directly correlates to the presence of bacteria commonly associated with urinary tract infections, making it the most relevant finding in this context.