What does it measure?
Some bacteria change nitrates naturally present in urine into nitrites. A dipstick checks for this chemical change. The test is often read with leukocyte esterase, urine microscopy, and the symptoms that led to testing.
Before the test
- Sample
- Collect urine in the laboratory’s container, following its clean-catch instructions.
- Timing
- The laboratory may request first-morning urine. Confirm the requested collection time.
What can the result mean?
A positive result supports the possibility of a urinary infection, but still needs context. A negative result does not rule one out: some bacteria do not make nitrite, and urine may not have stayed in the bladder long enough for the change to happen. [1]
When is it useful, and how is it read?
A positive result is most useful alongside urinary symptoms, white-cell findings, and a well-collected sample. Bacteria without symptoms require a different approach; pregnancy and certain urinary procedures are important exceptions to usual management. [1] [2]
Reading the results together
| Marker | What it adds |
|---|---|
| Urine Nitrite | A chemical clue produced by some bacteria. |
| Urine Leukocyte Esterase | A strip reaction linked to white cells. |
| Urine Pus Cells / WBCs (microscopic) | White cells seen under the microscope. |
Read these with symptoms. A culture answers a different question about which bacteria are present. [1] [3]
What can affect it?
Collection technique, frequent urination, and sample handling affect reliability. An old or contaminated sample can be misleading. The presence of bacteria without symptoms is handled differently from a symptomatic infection, including specific considerations during pregnancy. [1] [2]
Myth: «A negative nitrite rules out a UTI»
Some bacteria do not make nitrite, and frequent urination may leave too little time for it to form. Symptoms can still justify assessment even with a negative strip. [1] [2]
Questions you might have
Can nitrite be negative even with an infection?
Yes. Some bacteria do not produce nitrite, so urinary symptoms still need assessment. [1]
Does nitrite tell us which antibiotic will work?
No. If needed, a urine culture identifies bacteria and can test which antibiotics they respond to. [1]
What comes next?
If you have burning or frequent urination despite a negative strip, contact your clinician. A urine culture may be useful. Fever or flank pain needs prompt assessment rather than waiting for another home strip. [1] [2]
If nitrite is negative but I have symptoms, would a urine culture help?
The reference interval and units on your report are part of understanding your result. Understand units, reference intervals, and treatment targets.
Sources & references
Medical references & original research
- MedlinePlus — Nitrites in urine
- IDSA — Asymptomatic Bacteriuria Guideline (2019)
- MedlinePlus — Leukocyte esterase
- Mayo Clinic — Urinalysis
Books we consulted
References that informed our explanations of the test and its context.
- Pagana KD, Pagana TJ, Pagana TN. Mosby’s Diagnostic and Laboratory Test Reference. 14th ed. Elsevier; 2019.
Practical-section sources accessed: .
For general health education. Interpreting your result and deciding on tests or treatment requires your health context and a qualified clinician.
