urinalysis

PMLS Urine Analysis: Specimen Collection and Analyzing Urine

Historical Context

  • Hippocrates (5th BCE): Wrote extensively on uroscopy.

  • Middle Ages: Increased focus on the art of uroscopy in medical training.

  • 1140 CE: Introduction of color charts describing 20 different urine colors.

  • 1627: Thomas Bryant published on "pisse prophets".

  • 17th Century: Microscope invention allowed for sediment examination; Thomas Addis developed methods for quantifying urine sediments (Addis count).

  • 1827: Richard Bright included urinalysis in routine patient examinations.

Urine Composition

  • Primary Components:

    • Water: 95%

    • Solutes: 5%

  • Solute concentration influenced by dietary intake, physical activity, metabolism, and endocrine functions.

  • Organic Component: Urea

  • Inorganic Component: Chloride

Hormones Related to Urine Analysis

  • Aldosterone: Source - Adrenal Cortex

  • Antidiuretic Hormone: Source - Posterior Pituitary Gland

  • Erythropoietin: Source - Kidney

Normal Urine Volume

  • Normal Daily Output: 1200 to 1500 mL (600-2000 mL considered normal).

  • Conditions:

    • Polyuria: >2.5 L/day (>2.5 – 3 mL/kg/day in children)

    • Oliguria: <400 mL/day in adults (<1 mL/kg/hr in infants, <0.5 mL/kg/hr in children)

    • Anuria: Cessation of urine flow

    • Dysuria: Painful urination

    • Nocturia: Increased urine volume at night

    • Polydipsia: Increased water intake

Specimen Collection Importance

  • Helps in:

    1. Monitoring wellness.

    2. Diagnosing urinary tract infections.

    3. Monitoring progress in metabolic diseases.

    4. Evaluating therapy effectiveness and therapy-related complications.

Factors Affecting Accuracy of Urine Analysis

  • Collection Method

  • Container Use

  • Transportation

  • Timeliness of Testing

Containers

  • Specifications:

    • Clear, clean, dry, leak-proof.

    • Wide mouth for easier collection.

    • Sterile containers for microbiologic studies.

    • Adhesive bags for pediatric specimens.

    • Large containers for 24-hour collections.

  • Transfer Equipment:

    • Transfer straw with evacuated tube holder for sterile transfer.

Specimen Labeling

  • Must include:

    • Patient’s name

    • Identification number

    • Date and time of collection

    • Additional info such as age, location, provider’s name.

  • Labels must match laboratory requisition forms.

Specimen Rejection Criteria

  1. Unlabeled containers

  2. Misaligned labels and requisition forms

  3. Contamination with feces or toilet paper

  4. Contaminated container exteriors

  5. Insufficient quantity

  6. Improperly transported specimens

Specimen Handling

  • Refrigeration: Standard preservation method (2°C to 8°C).

  • Cultures: Should remain refrigerated until cultured for a maximum of 24 hours.

  • Chemical Preservatives: May be added if refrigeration is impractical.

Types of Specimens

Random Specimen

  • Common due to ease of collection, used for routine screening but can be affected by recent dietary intake.

First Morning Specimen

  • Ideal for screening; concentrated sample for better detection of chemicals.

GTT/Timed Specimens

  • Varying time frames to test glucose and ketones, aiding in glucose metabolism analysis.

  • Requires 24-hour collection methods and accurate volume measurement.

Catheterized Specimen

  • Collected under sterile conditions, often for bacterial culture.

Midstream Clean-Catch Specimen

  • Less invasive alternative to the catheterized approach, also for cultures.

Special Specimens

Suprapubic Aspiration

  • Provides contamination-free specimen for culture and cytologic examination.

Prostatitis Testing

  • Three-Glass Collection: Three separate urine samples to compare cell counts for prostatic infection.

  • Pre- and Post-Massage Test: Urine collections before and after prostate massage to check for significant bacteriuria.

Pediatric Specimens

  • Use of hypoallergenic adhesive bags or sterile collection via catheterization.

Drug Specimen Collection

  • Chain of Custody: Documentation process from collection to lab results.

  • Temperature checks within 4 minutes of collection to confirm integrity.

Common Urine Tests

Routine Urinalysis (UA)

  • Often used to screen for urinary and systemic disorders, analyzing physical, chemical, and microscopic properties.

Culture & Sensitivity (C&S)

  • Used for urinary tract infections, culturing specimens on nutrient mediums to identify pathogens.

Urine Cytology Studies

  • Identify cancer or viral infections; requires fresh clean-catch specimens.

Urine Drug Testing

  • Monitors drug usage, including recreational and prescription drug use.

Urine Glucose and Ketone Testing

  • Screens for diabetes and diabetic ketoacidosis monitoring.

Urine Pregnancy Testing

  • Confirms pregnancy via HCG levels, preferably using first morning urine.

Physical Examination of Urine

  • Odor: Often not clinically significant; can indicate certain conditions (fruity, ammonia).

  • Clarity: Normal urine should be clear; cloudiness indicates sediments.

  • Color: Ranges from pale yellow to amber, indicating hydration and potential pathological conditions.

Abnormal Urine Color Indicators

  • Dark Yellow: Concentration; Amber: Dehydration;

  • Yellow Orange: Bilirubin; Red: Hematuria or myoglobinuria.

Urine Clarity Terminology

  • Clear: No particulates; Hazy: Few particulates; Cloudy/Turbid: Many particulates.

Urine Specific Gravity

  • Evaluates urine concentration; normal range is 1.003 to 1.035.

  • Measured using urinometer, refractometer, and reagent strips, with corrections for protein and glucose content.

Urine Odor

  • Normal is aromatic; significant odor changes may indicate metabolic issues.

Chemical Examination of Urine Using Reagent Strips

  • Provides rapid analysis of key chemical components; requires careful technique to avoid errors.

Microscopic Examination of Urine

  • Reporting includes RBCs, WBCs, casts, crystals, and bacteria per standardized metrics.