Urinalysis Overview and Components

Urinalysis Overview

• Urinalysis is the analysis of urine
• Urine is formed in the kidneys as an ultrafiltrate of plasma
• Urine is the most analyzed body fluid in the body
• Reasons for using urine as a specimen: easily available, easily collected, contains information about the body's major metabolic functions, and inexpensive laboratory testing can be performed. It is useful for assessing kidney function and disease.

Components of Normal Urine

• Urea: Primary organic component, product of protein and amino acid metabolism
• Creatinine: Product of creatine metabolism by muscles
• Uric acid: product of nucleic acid breakdown in food and cells
• Chloride: Primary inorganic component found in combination with sodium (table salt). Associated with other inorganic substances
• Sodium: Primarily from salt intake. Combined with chloride and other salts
• Potassium: Primarily from intake of salt. Combined with chloride and other salts
• Phosphate: Combines with sodium to maintain blood pH balance.
• Ammonium: Regulates blood and tissue fluid pH
• Calcium: Combines with chloride, sulfate, and phosphate

Types of Specimens

• Random Specimen: Collected anytime; collection time is recorded
• First Morning or 8-hour Urine Specimen: Collected immediately after an 8-hour sleep. Ideal for screening purposes and for evaluating orthostatic proteinuria (preventing false negative pregnancy tests).
• Fasting Specimens: A second morning or second specimen voided after fasting (used for glucose monitoring)
• Timed Specimens: Can be fasting or not fasting. Multiple durations available (1/2 hour, 1 hour, 2-hour post-prandial, or 24-hour). 24-hour specimens are used to measure substances that change throughout the day
• Catheterized Specimen: Collected under sterile conditions, using a catheter to empty the bladder. Often used for bacterial cultures.
• Midstream Clean-Catch Specimen: Safer than catheterization, using sterile collection to avoid contamination. More representative of the actual urine.
• Suprapubic Aspiration: Collecting sample by inserting a needle into the bladder. Used for bacterial culture and cytology examinations
• Pediatric Specimen: Using soft, clear hypoallergenic bags that attach to the cleaned genital area. Option for catheterization or suprapubic aspiration

24-Hour Urine Specimen Procedures

• Empty the bladder upon waking
• Label container with time and date of collection
• Collect all urine for 24 hours, refrigerating if instructed
• Collect urine prior to bowel movements
• Drink fluids as needed to prevent dehydration
• Take a final void at end of 24 hours
• Seal container and transport to lab ASAP

Physical Examination: Color

• Color varies from colorless to black
• Normal color: pale yellow to dark yellow. Yellow color comes from the pigment urochrome.
• Other colors may be due to:
• Dark yellow/amber: bilirubin
• Yellow-orange: azo-gantrisin compounds
• Red: blood
• Brown/black: melanin, homogentisic acid, levodopa, methyldopa, phenol derivatives
• Blue/green: bacterial infections, Pseudomonas species infections
• Specific colors can have corresponding clinical or lab results

Physical Examination: Clarity

• Clarity refers to the transparency or turbidity
• Common terms:
• Clear
• Hazy
• Cloudy
• Turbid
• Milky
• Specific terms of clarity along with description of clarity determination

Physical Examination: Odor

• Not part of routine urinalysis. Freshly voided urine usually has a faint aromatic odor
• Other odors:
• Aromatic: normal
• Foul-ammonia: UTI, bacterial decomposition
• Fruity/sweet: diabetes mellitus, starvation, vomiting
• Maple syrup: maple syrup urine disease
• Mousy: phenylketonuria
• Rancid: tyrosinemia, isovaleric acidemia
• Sweaty feet: methionine malabsorption
• Cabbage: contamination
• Bleach: contamination

Chemical Examination: Reagent Strip

• Consist of chemical-impregnated absorbent pads attached to plastic strips.
• Color producing reaction occurs when in contact with urine.
• Results are interpreted by comparing strip color with a supplied colour chart (timed)
• Includes tests for: -pH
• Specific gravity
• Ascorbic acid
• Creatinine
• Protein
• Blood
• Nitrite
• Urobilinogen
• Bilirubin
• Ketones
• Glucose
• Leukocyte.

Chemical Examination: Reagent Strip Handling and Storage

• Store in a tightly closed opaque container below 30°C with a desiccant
• Do not open container in presence of volatile fumes
• Do not use expired strips
• Avoid moisture, volatile chemicals, and light

Chemical Examination : Reagent Strip Technique

• Proper mixing of specimens
• Correct dipping duration
• Removal from urine and blotting to avoid color bleeding
• Comparison with appropriate timed colour chart

Urinalysis Procedure Steps

• Check requests and labels
• Record physical characteristics (color, clarity)
• Collect 3-5 ml urine on labeled container
• Immerse reagent strip in urine for the specified time
• Remove strips and compare to chart for results
• Record results
• Centrifuge, decant, examine sediments under microscope for cells/elements.
• Record results
• Provide signed reports for general receiving and releasing area.

Reference

• Include reference details when needed for assignment