URINALYSIS

• Urine analysis


  Testing of urine with procedures commonly performed in an expeditious, reliable, safe and cost-effective manner
• Urine formation


  1. Ultrafiltrate of plasma

  2. Formed at kidneys

  3. Reabsorption of water and filtered substances essential to body function converts approximately 170,000 mL of filtered plasma to the average daily urine output of 1200 mL
• Normal daily urine output

  • 1200-1500mL
  • 600-2000mL also considered normal
• Oliguria


  • Decreased urine output: 400mL/day (adults)
  • Occurs at excessive water loss
• Anuria


  • Cessation of urine flow
  • Suggests severe kidney damage
• Nocturia


  Increased excretion of urine during the night
• Polyuria


  Increased urine output: >2.5L / day (adults)
• Urine composition


  • Urine is normally 95% water and 5% solutes (organic and inorganic)
  • Concentration of solutes influenced by: dietary intake, physical activity, body metabolism, endocrine functions
• Primary organic component of urine

  • Urea
• Primary inorganic component of urine

  • Chloride
• Hormones in urine


  • Aldosterone (adrenal cortex)
  • Antidiuretic hormone (posterior pituitary gland)
  • Erythropoietin (kidney)
• Organic solutes in 24-hour urine specimen

  • Urea (25.0-35.0g)
  • Creatinine (1.5g)
  • Uric acid (0.4-1.0g)
  • Hippuric acid (0.7g)
  • Others (2.9g)
• Inorganic solutes in 24-hour urine specimen


  • NaCl (15.0g)
  • Potassium (3.3g)
  • Sulfate (2.5g)
  • Phosphate (2.5g)
  • Ammonium (0.7g)
  • Magnesium (0.1g)
  • Calcium (0.3g)
• Urine should be analyzed within 1 hour of voiding
• Effects of prolonged sitting of urine specimens at room temperature

  • Increase: nitrate, pH, turbidity
  • Decrease: glucose, ketones, bilirubin, urobilinogen, cells and casts
• Urine is classified as a biohazard
• Urine is the most frequently analyzed non-blood body fluid
• Accurate urine test results depend on collection method, container used, specimen transportation and handling, and timeliness of testing
• Grounds for specimen rejection

  • Specimens in unlabeled containers
  • Nonmatching labels and requisition form
  • Specimens contaminated with feces or toilet paper
  • Containers with contaminated exteriors
  • Specimens of insufficient quantity
  • Specimens that have been improperly transported
• Containers for routine urine analysis

  • Clean and dry (sterile)
  • Leak proof
  • Screw top lids
  • Wide mouth
  • Made of clear material
  • Recommended capacity: 50mL
  • Labelled (name, DOB, hospital number, date & time)
• Disposable, non-sterile, plastic containers are most commonly used for urine collection (capacity: 50 mL)
• Urine from infants


  Pliable polyethylene bags with adhesive
• 24-hour urine collection


  Large, wide-mouthed plastic containers are used
• Urine for bacterial culture

  Sterile plastic containers
• After collection, urine samples must be sent to the laboratory and tested within 2 hours
• If urine cannot be delivered within 2 hours, the sample should be refrigerated or an appropriate preservative added
• Color of urine


  Varies from almost colorless to black, due to normal metabolic functions, physical activity, ingested materials or pathologic conditions
• Normal urine color


  • Pale yellow
  • Yellow
  • Dark yellow
  • Amber
• Yellow color of urine

  Caused by the presence of a pigment called urochrome
• Care should be taken to examine the specimen under a good light source, looking down through the container against a white background
• Abnormal urine colors


  • Dark yellow or amber - presence of the abnormal pigment bilirubin
  • Yellow-orange - administration of phenazopyridine (Pyridium) or azo-gantrisin compounds to persons with urinary tract infections
  • Red - presence of blood
  • Brown urine containing blood - glomerular bleeding
  • Brown or black - melanin or homogentisic acid, levodopa, methyldopa, phenol derivatives, and metronidazole (Flagyl)
  • Blue/green - bacterial infections, including urinary tract infection by Pseudomonas species and intestinal tract infections resulting in increased urinary indican
• Causes of urine color

  • Colorless - Recent fluid consumption, Polyuria or diabetes insipidus, Diabetes mellitus
  • Pale yellow - Dilute random specimen
  • Dark yellow - Concentrated specimen, D complex vitamins, Dehydration, Bilirubin, Acriflavine, Narofurantoin, Phenazopyridine (Pyridium), Phenindione
  • Orange-yellow - Bilirubin oxidized to biliverdin
  • Yellow-green - Pseudomonas infection
  • Green - Amitriptyline
  • Blue-green - Methocarbamol (Robaxin), Clorets, Phenol
  • Pink - RBCs
  • Red - Hemoglobin
  • Port wine - Myoglobin
  • Red-brown - Beets, Rifampin, Menstrual contamination
  • Brown - Porphyrins, RBCs oxidized to methemoglobin, Myoglobin
  • Black - Homogentisic acid (alkaptonuria), Malignant melanoma, Melanin or melanogen, Phenol derivatives, Argyrol (antiseptic), Methyldopa or levodopa, Metronidazole (Flagyl)
• Clarity of urine


  Refers to the transparency or turbidity of a urine specimen
• Terms used to report urine clarity

  • Clear
  • Hazy
  • Cloudy
  • Turbid
  • Milky
• Clear urine


  No visible particulates, transparent
• Hazy urine


  Few particulates, print easily seen through
• Cloudy urine


  Many particulates, print blurred through
• Turbid urine


  Print cannot be seen through urine, may precipitate or be clotted
• Procedure for evaluating urine color and clarity:
• Urine odor


  Freshly voided urine has a faint aromatic odor. Unusual odors can be caused by bacterial infections (strong unpleasant ammonia-like odor) or diabetic ketones (sweet or fruity odor)