Abstract
Urine specimens are usually requested for urine examination or urinalysis (UA), which is one of the most commonest ordered tests. The results of UA are used to diagnose, treat, and provide follow-up for a variety of conditions, especially urinary tract infections (UTIs), kidney disorders, liver problems and diabetes.
In general, urinalysis is obtained for symptoms of irritation, burning, pain, change in frequency of urination, or change in appearance of the urine. urinalysis is an essential procedure for patients undergoing hospital admission or physical examination and for a pregnancy checkup.
Two unique characteristics of urine specimens can account for urine analysis continued popularity:
- Urine is a readily available and easily collected specimen.
- Urine contains information about many of the body’s major metabolic functions, and this information can be obtained by simple laboratory tests.
Urine constituents
Urine consists of urea and other organic and inorganic chemicals dissolved in water. Considerable variations in the concentrations of these substances can happen as a result of the influence of factors such as dietary intake, physical activity, body metabolism, endocrine function, and even body position.
Urea, a metabolic waste product produced in the liver from the breakdown of protein and amino acids, accounts for almost half of the total dissolved solids in urine. Other organic substances include primarily creatinine and uric acid. The major inorganic solid dissolved in urine is chloride, followed by sodium and potassium.
Other substances found in urine include:
- hormones,
- vitamins,
- medications.
Although they are not a part of the original plasma filtrate, the urine may also contain formed elements such as cells:
- casts,
- crystals,
- mucus,
- bacteria. I
An increase in amounts of these formed elements are often indicative of disease.
Collection of Urine specimens
- Specimens should be collected in clean, dry, leak-proof disposable containers.
- They should be made of a clear material to allow for determination of color and clarity.
- The recommended capacity of the container is 50 mL, which allows 12 mL of specimen needed for microscopic analysis and additional specimen for repeat analysis.
Specimen Integrity:
Following collection, specimens should be delivered to the laboratory promptly and tested within 2 hours.
A specimen that cannot be delivered and tested within 2 hours should be refrigerated or have an appropriate chemical preservative added.
The 11 most significant changes that may occur in a specimen allowed to remain unpreserved at room temperature for longer than 2 hours are included in the following table:
 Preservation of Urine
The most routinely used method of preservation is refrigeration at 2 C to 8 C, which decreases bacterial growth and metabolism. Refrigeration can increase the specific gravity, when measured by urinometer, and the precipitation of amorphous phosphates and urates, which may obscure the microscopic sediment analysis. The specimen must return to room temperature before chemical testing by reagent strips. This will correct the specific gravity and may dissolve some of the amorphous urates.
When a specimen is to be transported over a long distance and refrigeration is impossible, chemical preservative like as thymol, boric acid, Formalin can added. The ideal preservative should be bactericidal, inhibit urease, and preserve formed elements in the sediment. At the same time, the preservative should not interfere with chemical tests.
NB: Unfortunately, the ideal preservative does not exist; therefore, a preservative that best suits the needs of the required analysis should be chosen
Types of Urine specimens
1. Random Specimen
This is the most commonly received specimen because of its ease of collection and convenience for the patient. The random specimen may be collected at any time. The random specimen is useful for routine screening tests to detect obvious abnormalities. But it may also show erroneous results resulting from dietary intake or physical activity just before collection. The patient will then be requested to collect additional specimens under more controlled conditions.
2. First Morning Specimen
This is the ideal screening specimen. It is also essential for preventing false-negative pregnancy tests. The first morning specimen, or 8-hour specimen, is a concentrated specimen, thereby assuring detection of chemicals and formed elements that may not be present in a dilute random specimen. The patient should be instructed to collect the specimen immediately on arising and to deliver it to the laboratory within 2 hours.
3. Fasting Specimen (Second Morning)
A fasting specimen differs from a first morning specimen by being the second voided specimen after a period of fasting. This specimen will not contain any metabolites from food ingested before the beginning of the fasting period. It is recommended for diabetic screening/monitoring.
4. 2-Hour Postprandial Specimen
The patient is instructed to void shortly before consuming a routine meal and to collect a specimen 2 hours after eating. The specimen is tested for glucose, and the results are used primarily for monitoring insulin therapy in persons with diabetes mellitus.
5. Midstream Clean-Catch Specimen
The midstream clean-catch specimen provides a specimen that is less contaminated by epithelial cells and bacteria and, therefore, is more representative of the actual urine than the routinely voided specimen.
The following should be considered:
- Patients must be provided with appropriate cleansing materials, a sterile container, and instructions for cleansing and voiding.
- Patients are instructed to wash their hands before beginning the collection. Male patients should clean the glans and withdraw the foreskin.
- Female patients should separate the labia and clean the urinary meatus and surrounding area. When cleansing is complete, patients are to void first into the toilet, then collect an adequate
- amount of urine in the sterile container, and finish voiding into the toilet. Care should be taken not to contaminate the specimen container.
Also check out Phlebotomy
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