What is the clinical significance of positive urine nitrite

For healthy people, the laboratory qualitative test of urine nitrite is negative. However, when patients have urinary tract infection, the urine nitrite is often positive due to bacteria. For example, when Escherichia coli causes urinary tract infection, the urine nitrite test is positive during laboratory examination. In addition to urinary tract inflammation, nephritis and pyelonephritis may also cause such symptoms. Its clinical significance lies in scientific diagnosis, which helps to provide timely treatment and avoid causing lasting harm to the patient's health. Urinary tract infections can be diagnosed by culturing urine for bacteria.

Clinical significance

Its positive rate depends on the urine remaining in the bladder for more than 4 hours, and the positive rate can reach 80%. A positive result indicates that there are more than 100,000 bacteria/ml in the urine.

Positive results of urine nitrite are commonly seen in: pyelonephritis caused by Escherichia coli, the positive rate of which accounts for more than two-thirds of the total; symptomatic or asymptomatic urinary tract infections, cystitis, bacteriuria, etc. caused by Escherichia coli and other Enterobacteriaceae.

A negative urine nitrite test does not mean that there is no bacterial infection. It is just that urinary tract infections caused by certain bacteria that do not have the ability to reduce nitrates cannot show a positive result. These bacteria include non-fermenting bacteria such as Acinetobacter or urine cannot be retained in the bladder for more than 4 hours.

Note: A negative result may also occur if the bacteria in the UTI cannot reduce nitrates to nitrites, if the urine is not retained in the bladder for a long time, or if there is a lack of nitrates in the urine.

Some urinary tracts contain Gram-negative bacteria that reduce nitrates, a product of protein metabolism in urine, to nitrites. Therefore, determining whether there is nitrite in urine can quickly and indirectly determine the status of urinary tract bacterial infection. Clinically, the incidence of urinary tract infection is high, and sometimes the infection is asymptomatic, especially in female patients. Diagnosis of a urinary tract infection requires a urine culture.

Urine occult blood alone cannot be used as a basis for diagnosing a disease, because normal people may also have urine occult blood under normal circumstances, but normal urine occult blood is negative. Normal urine contains very few red blood cells, so based on the overall situation, your situation needs to be considered to be caused by a urinary tract infection.