Lab

Urine Nitrite

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Urine Nitrite, Urine Dipstick Nitrite

  • See Also
  1. Urinalysis
  2. Urine Leukocyte Esterase
  • Mechanism
  1. Some Bacteria (E. coli, Klebsiella, Proteus) reduce urine nitrates to nitrites
    1. Many other Bacteria do NOT reduce urine nitrates (e.g. Enterococcus, Pseudomonas, Acinetobacter)
  2. Nitrite production typically requires urine standing (in Bladder) for at least 4 to 6 hours
    1. Infants do not hold their urine, and do not typically demonstrate nitrite on the urine sample
  • Efficacy
  1. Test Specificity: >91%
  2. Test Sensitivity: <49%
  • Interpretation
  1. Normal: Negative
  2. Positive
    1. Urinary Tract Infection
    2. Gross Hematuria
  1. Vaginal contaminant
  2. Phenazopyridine
  3. Dipstick exposed to air
    1. Close test strip containers immediately
    2. Strip exposed to air for 1 week: 33% False Positive
    3. Strip exposed to air for 2 weeks: 75% False Positive
  1. Increased Urine Specific Gravity
  2. Increased Urobilinogen
  3. Bacteria lacking nitrate reductase enzyme (e.g. Enterococcus)
  4. Urine pH <6.0
  5. Vitamin C supplementation
  6. Low nitrate diet
  7. Short Bladder incubation time (<4 hours)
  • References
  1. Hitzeman (2022) Am Fam Physician 106(1): 27-35 [PubMed]
  2. Simerville (2005) Am Fam Physician 71(6): 1153-62 [PubMed]