Introduction to Urinalysis

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Introduction to Urinalysis

• Laboratory Procedures

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Urinary System

• Designed to maintain a balance between fluid,
  electrolytes, and acid-base homeostasis by
  selectively eliminating waste products from the
  body.
• Urine is formed through glomerular filtration,
  tubular reabsorption, and tubular secretion
  (remember everything I taught you in AP).
• These are influenced by hormones
• Do you remember their names?

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Medical Terminology

• Pollakiuria
• Frequent urination
• Polyuria
• Increased urine output or production
• Oliguria
• Decrease in the formation or elimination of urine
• Anuria
• Complete absence of urine formation or
  elimination
• Dysuria
• Difficult urination

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Urinalysis

• Urine collection can be accomplished through
  mid-stream free catch, manual expression,
  catheterization, and cystocentesis.

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Advantages to Urinalysis

• Fast
• Simple
• Inexpensive
• Provides useful information (urinary tract and/or
  other body systems)

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Voided Urine Sample

• Easiest to obtain
• May be contaminated from distal genital tract
• Not satisfactory if examining for bacteria.

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Voided Urine Sample Collection

• Use a clean container
• Wasch prepuce or vulva (when possible)
• Try to collect mid-stream urine

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Disadvantages to Voided Sample

• Contamination
• Difficult in cats
• May be difficult in easily scared dogs and short
  breeds

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Expressing the Bladder

• Use steady gentle pressure
• Will feel like a balloon or ball under your
  hands.
• Make sure you are expressing in a squeezing
  motion where you are forcing urine down urethra.
• Wash external genitalia
• Contamination from lower urinary tract/genital
  tract is a concern.
• DO NOT DO MANUAL EXPRESSION WHEN THERE IS AN
  URETHRAL OBSTRUCTION!!!

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Urinary Catheterization

• Act of placing a catheter through urethra into
  bladder
• Advantages
• Less possibility of contamination from lower
  genital tract.
• Helpful in obese animals when bladder is
  difficult to palpate
• Disadvantages
• Trauma to sensitive urethral mucosa
• Possible contamination

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Cystocentesis

• Act of obtaining a urine sample via a needle and
  syringe directly from the bladder
• Advantages
• Sterile sample
• Disadvantages
• Difficult to obtain in obese animals
• Trauma to organs if not done correctly

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Urine Sample Preservation

• Analyze all urine within 30 minutes if possible
• May refrigerate for 6-12 hours if needed
• Bring to room temperature before anlaysis
• Morning samples are more concentrated
• If allowed to stand at room temperature, may get
  false results.

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Physical Characteristics of Urine

• Color
• Transparency
• Odor
• Specific gravity
• Volume

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Urine Color

• Normal color is due to pigments called urochromes
• Normal light yellow to amber color
• Abnormals
• Red blood (hematuria)
• Reddish-brown Hemoglobin or Myoglobin
• Dark yellow-brown Bilirubin (bilirubinuria)
• Orange-Reddish brown Normal in rabbits

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Urine Transparency

• Clear vs. Cloudy
• Cloudy could indicate increase cells, mucus,
  casts, crystals and bacteria.
• Horses have cloudy urine due to high content of
  mucus and calcium carbonate crystals.

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Urine Odor

• Not Very diagnostic
• Strong odor may suggesst bacterial urease
  production
• Male cats, goats, and pigs have a very strong
  urine odor

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Urine Specific Gravity

• Measure urine concentration which is dependent on
  the number, molecular size, and weight of urine
  solutes
• Measures the density of urine as it compares to
  water
• Specific gravity of water is always 1.000

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Normal Urine Specific Gravities

• Man 1.015-1.035
• Dog 1.015-1.040
• Cat 1.015-1.050
• Horse 1.015-1.045

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Methods of collecting a urine specific gravity

• Refractometer
• Reagent strip
• Urinometer

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Causes of Altered Specific gravity

• Increased specific gravity
• Dehydration
• Increase fluid loss
• Decreased water intake
• Decreased specific gravity
• Kidney disease
• Excessive water
• Pyometra
• Some drugs

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Urine Volume

• Influenced by several factors
• Water intake
• Size of animal
• Species of animal