CLINICAL LAB SCIENEC

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ESSENTIALS OF CLINICAL LABORATORY SCIENCE
Table 12-1 Common Urine Preservatives and Their Uses
Preservative
Sulfuric acid
Hydrochloric acid
Sodium carbonate
Sodium hydroxide
Boric acid
Refrigeration
Use
Preserves calcium
Preserves calcium, magnesium, and phosphorus
Preserves porphyrins, urobilinogen
Preserves myoglobin
Preserves creatinine, uric acid, protein, steroids, and glucose
Used for tests for protein, barbiturates, and drug abuse screen
In using the procedure of the urinalysis, it is also a simple matter to perform
screening tests on large populations in an economic fashion to determine certain
diseases that cause abnormal results in random urine samples.
Examination of Urine Sample
A great deal can be determined by an initial examination of a urine sample. The
color and clarity of the sample may provide important information. A scant specimen
of only a few drops or milliliters could indicate a medical problem and might
be noted as quantity not sufficient (QNS) on the laboratory report.
Usually, large automated analyzers are found in the largest laboratories with
high volumes of urine examinations. Functions of these machines include chemical
analyses as well as gross macroscopic (visible to the naked eye) and microscopic
evaluations. A macroscopic examination refers to the observation of physical properties
of the urine, including color, clarity, sufficient volume for analysis, and odor.
Significantly abnormal samples examined by these complex instruments may require
that these samples be examined manually by a technician or technologist-level
laboratory professional before releasing the report to the physician.
There are three separate types of examinations, made up of 10 components, that
comprise a complete urinalysis. Sometimes the physician will request only one of
these components of a urinalysis.
Macroscopic 1. Color
2. Volume
3. Character (turbidity or cloudiness)
Chemical 4. Specific gravity (by TS [total solids] meter) and/or dipstick as
a screen only
5. Urine chemical concentrations of protein, glucose, ketones,
bilirubin, blood, nitrites, urobilinogen, leukocytes, leukocyte
esterase (leukoesterase), and pH using a reagent strip method
(chemically impregnated reactive strips)
6. Confirmation of protein by sulfosalicylic acid (SSA)
7. Ketones by Acetest tablet method
8. Bilirubin by Ictotest tablet method
9. Reducing substances by Clinitest tablet method
Microscopic 10. Examination for microscopic components
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