MT305 LEC: Introduction to Urinalysis Week 1

Study Notes

History & Importance of Urinalysis

Analyzing urine is considered the beginning of laboratory medicine.
Historical references include cave drawings and Egyptian hieroglyphics, such as the Edwin Smith Surgical Papyrus.
Early physicians analyzed urine based on visual and sensory observations: color, turbidity, odor, volume, viscosity, and sweetness (attraction of ants).
Hippocrates authored a book on “uroscopy” in the 5th century BCE.
During the Middle Ages, urine examination became integral to medical training.
In 1694, Frederik Dekkers discovered albuminuria by boiling urine; normal urine should have no albumin.
"Pisse prophets," unqualified individuals, offered health predictions based on urine analysis, often criticized by authorities.
Galen noted the phenomenon termed "Diarrhea of Urine."
Medieval practitioners associated various diseases with urine characteristics, diagnosing based only on specimens.
The invention of the microscope in the 17th century revolutionized urinary sediment examination.
Thomas Addis developed methods to quantify microscopic sediment in urine analysis.
Richard Bright formally integrated urinalysis into routine patient examinations in 1827.
By the 1930s, the complexity of urinalysis tests made some practices impractical, leading to a decline in routine examinations.
The resurgence of modern testing methods has reinstated urinalysis as a vital part of medical evaluations.
Unique characteristics of urine that enhance its value in diagnostics:
- Easily collected and readily available specimen.
- Provides critical metabolic information through cost-effective laboratory tests.

Urine Volume

Normal daily urine output is between 1200-1500 mL.
Ranges from 600 to 2000 mL are considered normal.
Oliguria indicates reduced urine output:
- Infants: less than 1 mL/kg/hr
- Children: less than 0.5 mL/kg/hr
- Adults: less than 400 mL/day
Anuria refers to complete cessation of urine flow.
Nocturia is characterized by an increase in nighttime urination.
Polyuria signifies increased daily urine volume, linked to conditions such as diabetes insipidus (DI) and diabetes mellitus (DM):
- DI involves low production of vasopressin/ADH.
- DM results from insufficient insulin production:
  - Type I: Insulin-dependent.
  - Type II: Insulin-independent, often lifestyle-related.
- Adults: More than 2.5 L/day; Children: 2.5 to 3 mL/kg/day.

Urine Formation

Urine is formed as an ultrafiltrate of plasma.
The kidneys reabsorb water and essential substances filtered from the blood, contributing significantly to homeostasis.