Page 29 - Clinical Biochemistry

Urine is produced by the kidney to:
• Maintain constant plasma osmotic concentration.
• Regulate pH, electrolyte and fluid balances.
• Excrete solid waste products (mostly urea and sodium chloride).

Urinalysis

Urinalysis is the physical, chemical, and microscopic examination of urine. It involves a
number of tests to detect and measure various compounds that pass through the urine.

Purpose

Routine urinalysis are performed for several reasons:
• General health screening to detect metabolic diseases.
• Diagnosis of diseases or disorders of the kidneys or urinary tract.
• Monitoring of patients with diabetes.
• Pregnancy tests.

Specimen handling
• Urine should be processed within 1-2 hours of collection.
• If it cannot be processed in a timely manner, then either:

(1) Refrigerate the specimen at 2-8°C (specimen will be stable for 24 hours) or

(2) A preservative fluid (e.g. boric acid) is added and store at room temperature for up to 2 – 3
days (for culture).

Normal results for a typical urinalysis

Color Straw - Dark yellow Occult blood Negative

Appearance Clear - Hazy Leukocyte Esterase Negative

Specific Gravity 1.010-1.025 Nitrite Negative

pH 4.5-7.8 Urobilinogen 0.1-1.0 EU/dL