Lab

Urinalysis

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Urinalysis, Urine Exam, Urine Dipstick

  • Methods
  1. Multiple reagent test strip or automated machine
  2. Urine Microscopic Exam
  • Technique
  • Urine Collection
  1. See Clean Catch Urine Collection
  2. Refrigerate urine sample if prompt testing is not available
  3. Obtain "dirty urine" first if testing for Sexually Transmitted Infection
    1. See STD Screening
    2. First-Stream Urine without Urethral Cleansing ("Dirty Urine")
    3. Preferred sample in men and women (equivalent to endocervical, vaginal or Urethral swabs)
  • Labs
  • Urine Dipstick or Automated Machine Findings
  1. Background
    1. Read dipstick after 60-120 seconds of contact with urine
    2. Urine Leukocyte Esterase dipstick is most time sensitive
    3. Urine Nitrite dipstick will discolor if left in open air, unpackaged (False Positive)
  2. General Tests
    1. Urine Appearance (Urine Color)
    2. Urine Odor
    3. Urine Specific Gravity
    4. Urine pH
  3. Kidney and Urinary Tract Disease Tests
    1. Urine Protein
    2. Urine Blood
      1. Gross Hematuria
      2. Microscopic Hematuria
  4. Urinary Tract Infection Tests
    1. Urine Leukocyte Esterase
    2. Urine Nitrite
  5. Metabolic Disease Tests
    1. Urine Glucose
    2. Urine Ketones
    3. Urine Bilirubin
    4. Urine Urobilinogen
  1. Collection
    1. First morning sample
    2. Midstream, clean catch collection
    3. Minimum volume of 3 ml (1 ml for children)
    4. Analyze within 1-2 hours or refrigerate
  2. Preparation of spun urine for microscopy
    1. Start with 10 ml of midstream urine
    2. Centrifuge for approximately 10 minutes (typically at near 2000 rpm)
      1. Discard supernatant
      2. Suspend sediment in 0.3 ml saline or supernatant
    3. Examine under microscopy at 400x (oil immersion) magnification
      1. Review at least 10-20 microscopic fields
  3. Findings (based on spun urine)
    1. Urine Red Blood Cells
      1. Microscopic Hematuria if 3 RBC/hpf or higher
    2. Urine White Blood Cells
    3. Urine squamous epithelial cells
      1. Suggests vaginal contaminant if >5 squamous epithelial cells/hpf
    4. Urine Bacteria
  4. Advanced Method findings
    1. Urine Casts (Phase Contrast Microscope)
    2. Urine Crystals (Urine Crystals)
  • References
  1. Hitzeman (2022) Am Fam Physician 106(1): 27-35 [PubMed]
  2. Simerville (2005) Am Fam Physician 71(6): 1153-62 [PubMed]