Urine analysis
A urinalysis, or urine test, is a common medical test in which the urine is examined to diagnose and monitor various illnesses.
Urine Tests are useful in;
Urinary tract infections
Diabetes
Pregnancy
Liver disease.
1) Physical Examination
Introduction
Physical examination of urine is the first part of routine urinalysis. It is the simplest procedure of all urine examination, but this simplicity does not mean that any one can do it with out any background knowledge and experience. Physical examination of urine usually gives hint for the subsequent urinalysis. For example, white turbid urine sample may suggest to the technician the presence of Leukocytes (pus cells) and/or Epithelial cells in microscopic examination, and in chemical examination, with positive result of Nitrite.
1. Volume
Normally, 600 – 2000 ml of urine is voided per 24 hr.
Volume of urine excreted is related to:
- Individual fluid intake
- Body temperature
- Climate
- Individual’s health status
Abnormally higher amount (greater than 2000 ml/24) or very low amount i.e. less than 600 ml/24 occur mostly due to some pathological conditions.
2. Odor
Normally fresh voided urine from healthy individuals has faint aromatic odor, which comes from volatile acids, normally found in urine, mostly, ammonia.
3. Color
Normally color of urine may vary within a day; in the morning it has dark yellow color, while in the afternoon or evening, the color ranges from light yellow to colorless. Normal urine color varies from straw (light yellow color) to dark amber (dark yellow).
4. Appearance (Transparency)
Fresh voided urine specimen is normally clear and transparent. On long standing, due to chemical changes that occur in normal constituents of urine through time, as described in the introduction part of this lecture note, it becomes turbid.
5. pH
A test that determine acidity, neutrality or alkalinity of a solution.
pH 7 indicates neutrality.
pH < 7 indicate acidity.
pH > 7 indicate alkalinity.
Normally, freshly voided urine pH range from 5-7 in healthy individuals, and average is pH 6.
6. Specific Gravity of Urine
Specific gravity is defined as the ratio of the weight of a fixed volume of solution to that of the same volume of water at a specified temperature, usually 20o C (in some books 25o C). The specific gravity of urine has been used for years as measure of the total amount of material dissolved in it (total solids), and thus of the concentrating and excretory power of the kidneys.
2) Chemical Examination
- Proteins in urine can indicate kidney disease or kidney damage. They may also be present in urine after strenuous exercise and when dehydrated.
- Ketones in urine emerge when the body begins to break down fat as a source of energy. Ketones may be a sign of uncontrolled diabetes, starvation, alcohol abuse, or a condition known as diabetic ketoacidosis.
- Glucose (sugar) in urine can indicate diabetes or high blood sugar.
- Bilirubin in urine is a type of waste produced when old red blood cells break down. Bilirubin can indicate liver disease.
3) Microscopic examination
- RED BLOOD CELLS
Appearance:
- Normally RBCs appear in the fresh sample as intact, small and faint yellowish discs, darker at the edges
- - Measure 7-8 μm
- - In concentrated urine may be crenated, and their size became small (5-6 μm)
2. LEUKOCYTES (WBCs)
Normal range: 0-4 WBC/HPF.
Appearance:
- Normally, clear granular disc shaped,
- Measure 10-15 μm, the nuclei may be visible.
- In alkaline urine, they may increase their size and become irregular.
- Predominantly, polymorph nuclear neutrophils are seen.
3. EPITHELIAL CELLS
Normally few epithelial cells (0-2 / HPF) can be found
• Appearance
Their size differs depending on the site from which they originated.
4. CASTS
• Formed by precipitation of proteins, and aggregation of cells within the renal tubules. Most of them dissociate in alkaline urine, and diluted urine (specific gravity ≤ 1.010) even in the presence of proteinurea.
5. PARASITES
Parasites that can be seen in urine microscopy are:
- Trichomonas vaginalis
- Schistosoma haematobium
- Wuchereria bancroftie
* Other parasites also may occur due to contamination of the urine with stool.
6. YEAST CELL
Yeast cells are fungi that are not normally seen in health individuals.
Appearance
- - Variable in size
- - Colorless.
- - Oval in shape, and usually form budding.
- - Have high refractive index.
7. BACTERIA
Bacteria are the most common cause of UTI and aerobic gram negative bacilli, particularly, members of the enterobacteriacea, are the most dominant agents.
8. Non-organized Elements (Urine Crystals)
Appear usually after the specimen (urine) collected and left with out examination. Mostly occur during metabolic abnormalities and excessive consumption of certain foodstuffs. May be classified into acidic, basic, and both acidic and basic based on:
- pH of urine in which they are usually seen.
- Solubility characters.
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