What Are the Causes of a Positive Nitrite Test in Female Urine?

Nitrite in urine is a metabolic byproduct generated when bacteria break down nitrates. A positive nitrite test suggests a possible urinary tract infection (UTI). If the urinalysis also reveals an elevated white blood cell count—specifically, more than 5 white blood cells per high-power field—and the patient experiences symptoms such as urinary frequency, urgency, or dysuria, a UTI is highly likely.

If the patient has no symptoms of urinary frequency, urgency, or dysuria and the white blood cell count is not significantly elevated, the positive nitrite result may reflect improper urine specimen collection (e.g., contamination with environmental bacteria) or prolonged storage of the urine sample—particularly in warm weather—which can promote rapid bacterial growth.

If a UTI is confirmed, anti-infective therapy is required. Commonly prescribed antibiotics include amoxicillin, levofloxacin, and cefixime. However, if the urinalysis shows only a positive nitrite result without any other abnormalities—and the patient remains asymptomatic (i.e., no urinary frequency, urgency, or dysuria)—increasing fluid intake and frequent voiding are recommended, followed by repeat urinalysis in two days.