3. Random specimen
Random urine samples are used for
urinalysis, which can screen and diagnose
metabolic disorders and urinary tract
infections.
Morning sample
This sample is collected the first time the patient
urinates in the morning. A first voided specimen is the
most concentrated and is the preferred specimen for
pregnancy testing, bacterial cultures and microscopic
examinations.
4. .
Clean catch midstream
The clean-catch urine method is used to prevent germs from the
penis or vagina from getting into a urine sample.
Discard first few ml .
This is recommended for bacteriologic culture.
24-hour specimen
Urine samples are collected in one or more containers
over a period of 24 hours.
Store your urine from the 24-hour time period in a cool
environment. It can be kept in the refrigerator or on ice in
a cooler.
5. Postprandial specimem
• Postprandial urine glucose test is done on a
sample of urine
• collected 2 hours after a meal in the afternoon is
sometimes requested for estimation of glucose (to monitor
insulin therapy in diabetes mellitus) or of urobilinogen.
• Quantitative estimation of proteins or hormones.
Supra pubic aspired
• Suprapubic aspiration of urine is a simple and safe technique for
obtaining an uncontaminated specimen of urine in children.
• Children less than 6 months of age
6. If urine is collected ,but analysis is done after 8 hour what
are the change that happen in urine.
The urine sample should ideally be examined within 1-2
hours of voiding.
The sample can be kept in the refrigerator for a
maximum of 8 hours.
Refrigeration (4-6°C) is the best general method of
preservation up to 8 hours.
Before analysis, refrigerated samples should be warmed
to room temperature.
7. • Increase in pH due to production of ammonia from urea by
urease-producing bacteria.
• Formation of crystals due to precipitation of phosphates and
calcium (making the urine turbid).
• Loss of ketone bodies, since they are volatile.
• Decrease in glucose due to glycolysis and utilization of
glucose by cells and bacteria.
If urine is left standing at room temperature for
long after collection.
8. • Oxidation of bilirubin to biliverdin causing falsenegative test for
bilirubin.
• Oxidation of urobilinogen to urobilin causing falsenegative test for
urobilinogen.
• Bacterial proliferation.
• Disintegration of cellular elements, especially in alkaline and
hypotonic urine.
9. Preservation of Urine Sample
Refrigeration (4-6°C) is the best general method of
preservation up to 8 hours.
chemical preservatives can be added to the 24-hour
urine sample:
Hydrochloric acid: It is used for preservation of a 24- hour
urine sample for adrenaline, noradrenaline, vanillylmandelic
acid, and steroids.
Toluene: It forms a thin layer over the surface and acts as a
physical barrier for bacteria and air. It is used for
measurement of chemicals.
10. • Boric acid: A general preservative.
• Thymol: It inhibits bacteria and fungi.
• Formalin: It is an excellent chemical for
preservation of formed elements.
