Urine Microanalysis

Unit 2: Urine Microanalysis Study Notes

Optimal Urine Sample Collection

• Best Urine Sample: First morning sample is ideal, examined within 30 minutes of collection.

Documentation Requirements

• Recording Necessities:

  • Must accurately record everything observed, including incidental findings such as grass awn. (True)

• Four Key Items to Record on Urine Sheet:

  1. Time of collection

  2. Time of analysis

  3. Collection method

  4. Indication if the sample was pre-prandial.

Microscopic Evaluation

• 10X Power Evaluation: Common features evaluated include:

  1. Epithelial cells

  2. Casts

  3. Some crystals (notably struvite)

  4. Renal Tubular cells

• 40X Power Evaluation: Common features evaluated include:

  1. Leukocytes (white blood cells)

  2. Erythrocytes (red blood cells)

  3. Yeast

  4. Small crystals (including calcium oxalates, amorphous phosphates, urates, etc.)

  5. Some bacteria (higher magnification of 100X may be needed for some bacterial evaluations).

• Urine Sediment Analysis: Common evaluations include:

  1. Leukocytes (WBCs)

  2. Erythrocytes (RBCs)

  3. Epithelial cells

  4. Microorganisms (yeast, bacteria, etc.)

  5. Casts

  6. Crystals

  7. Sperm (in intact males)

  8. Other components (such as mucous, debris, fat droplets, parasites, etc.).

Specific Terms and Conditions

• Term for Excessive Leukocytes: Pyuria (an excess of white blood cells in urine).

• Checking for Iatrogenic Results: If a urine sample was taken via cystocentesis and hematuria is noted, verify accuracy by rechecking with a free catch midstream urine sample.

Epithelial Cells

• Types of Epithelial Cells

  1. Squamous Epithelial Cells

  2. Transitional Epithelial Cells

  3. Renal Epithelial Cells

• Cystocentesis Implications: A sample collected via cystocentesis should not contain bacteria (True).

Yeast Identification

• Yeast may be confused with Red Blood Cells (RBCs); RBCs do not dissolve in 2% acetic acid and typically show budding characteristics.

Urinary Casts

• Definition: A urinary cast is a coagulated protein that forms within and is produced by the renal tubules.

• Normality of Casts: A small number of casts in urine can be normal, but larger numbers indicate renal tubular damage (False).

• Pathological Indication: Casts generally indicate a pathologic change in the renal tubules that may be mild or of a transient nature.

• Types and Commonality of Casts:

  1. Hyaline cast

  2. Granular casts

  3. Epithelial cast

  4. Waxy cast

  5. Fatty cast

  • Most Common Cast: Granular casts are the most common.

Crystals in Urine

• Terminology: The term for crystals in urine is Crystalluria.

• Crystal Types Based on Urine pH:

  • Alkaline Urine:

    • Magnesium Ammonium Phosphate

    • Amorphous phosphates

    • Ammonium urate

    • Calcium carbonate crystals (especially noted in horses)

  • Acidic Urine:

    • Amorphous urates

    • Uric acid crystals (found mainly in Dalmatians)

    • Calcium oxalate crystals

• Triple Phosphate Crystals' Alias: Known as magnesium ammonium phosphate or struvite crystals.

• Appearance of Struvite Crystals: They are described as looking like coffin lids.

Pathology Indications

• Crystals in Ethylene Glycol Intoxication: If a U/A is performed on a patient suspected of ethylene glycol intoxication, Calcium Oxalate Crystals may be observed.

• Breed Predisposition: Dalmatians are more predisposed to the formation of urate crystals.

• Cystine Crystals: Often occur due to a hereditary defect within the kidney, which appears to be linked to sex (specifically androgens) and is dependent on intact male dogs.

• Species with Calcium Carbonate Crystals: Commonly observed in horses, rabbits, guinea pigs, and goats.

• Clinical Significance of Amorphous Crystals: Amorphous crystals are noted to have no significant clinical implications (False).

Additional Observations in Urine Analysis

• Other Observables in U/A Samples:

  1. Mucous threads

  2. Spermatozoa

  3. Parasites

  4. Fat droplets

  5. Artifacts