A urinalysis shows nitrites and leukocyte esterase; what diagnosis is most likely?

• A. Urinary tract infection
• B. Acute kidney injury
• C. Acute appendicitis
• D. Kidney stones

Answer: (A)

Nitrites and leukocyte esterase in urine point to a urinary tract infection. Leukocyte esterase signals white blood cells in the urine, showing inflammation, while nitrites indicate bacteria that convert nitrates to nitrites—an association common with organisms that cause UTIs (like E. coli). Together, they create a strong clue for an infection of the urinary tract.

Acute kidney injury isn’t defined by this nitrite/esterase pattern; it’s about impaired kidney function and may show different clues like changes in creatinine, BUN, or casts. Acute appendicitis centers on abdominal pain and systemic signs with little expectation of a distinctive urinalysis nitrite/esterase pattern. Kidney stones often cause flank pain and hematuria rather than a consistent nitrite and leukocyte esterase signal.