Urine nitrites
What it measures, and what changes the number.
This dipstick test checks for nitrite in urine. Urine naturally contains nitrate from the diet, and certain bacteria can convert nitrate into nitrite, so the test is an indirect sign of bacteria in the sample.
It is read together with the rest of the urinalysis, such as urine pH, protein and specific gravity, and often with a white cell test on the same strip and a urine culture when one is ordered.
The conversion takes time, so urine that has been in the bladder for several hours, such as a first morning sample, is preferred. Not all bacteria produce nitrite. A sample left standing at room temperature can allow bacteria to grow and change the reading, and very dilute urine or vitamin C can weaken the reaction. Results are reported as negative or positive. Reports may list it as Nitritos.
Often read alongside: Urine pH, Urine protein, Urine specific gravity