Physical Properties
Urinalysis (UA) includes an assessment of the physical properties of urine, which provide important information about the patient's health status.
1. Color
Normally, urine has a yellow color, ranging from pale yellow to amber. The color is due to urochromes — pigments formed during hemoglobin breakdown. Factors affecting color intensity include:
- Hydration status: drinking large amounts of fluids makes urine lighter; dehydration darkens it.
- Diet and medications: consumption of beets, carrots, blueberries, and certain drugs can change urine color.
- Pathological conditions: for example, hematuria may cause reddish urine, bilirubinemia — dark brown.
2. Clarity
Freshly collected urine in a healthy person should be clear. Cloudiness may indicate the presence of:
- mucus,
- salts,
- bacteria,
- cellular elements (leukocytes, erythrocytes),
- fat droplets.
Cloudiness is often associated with inflammatory processes in the urinary tract.
3. Odor
Normally, urine has a faint characteristic odor. Changes in odor may indicate various conditions:
- strong ammonia smell — bacterial infections,
- acetone smell — ketonuria (e.g., diabetes),
- foul putrid odor — purulent processes.
4. Specific Gravity
Specific gravity reflects the kidney's concentrating ability and depends on the amount of dissolved substances in urine. Normal values:
- adults: 1010–1025,
- children: 1002–1030 (depending on age).
Increased specific gravity may be observed in dehydration, diabetes mellitus, nephrotic syndrome. Decreased — in renal failure, diabetes insipidus.
5. pH
Urine pH ranges from 4.5 to 8.0. Factors affecting acidity include:
- Diet: meat-based diets acidify urine, plant-based diets alkalize it.
- Infections: bacterial infections may raise pH.
- Metabolic conditions: e.g., diabetes causes more acidic urine.
These physical characteristics of urine are important diagnostic indicators and assist in detecting various urinary system and metabolic diseases.