| |
or profuse sweating reduces urinary output; a
high-protein diet tends to increase it. Daytime urine
output is normally two to four times greater than
nighttime output.
PRESERVATION OF URINE SPECIMENS
To delay decomposition of urine, use the following
methods of preservation:
· Refrigeration
· Preservatives
—Hydrochloric acid
—Boric acid
—Glacial acetic acid
Other preservatives used include formaldehyde,
toluene, and thymol. The preservative used must be
identified on the label of the container.
If no
preservative is used, this, too, should be noted.
NOTE: Before adding a preservative to a
urine specimen, contact the laboratory
performing the test to find out what
preservative to use and the quantity to
add. Preservative requirements vary from
laboratory to laboratory.
ROUTINE URINE EXAMINATION
A routine urinalysis includes the examination of
physical characteristics, chemical characteristics, and
microscopic structures in the sediment. A sample for
urinalysis (routine and microscopic) should be at least
15 ml in volume (adult), and either a random or first
morning specimen.
Children may only be able to
provide a small volume, but 10-15 ml is preferred.
Physical Characteristics
Physical characteristics evaluated during a routine
urinalysis include color, appearance, and specific
gravity.
COLOR.—The normal color of urine varies from
straw to light amber. Diluted urine is generally pale;
concentrated urine tends to be darker. The terms used
to describe the color of urine follow.
· Colorless
· Light straw
· Straw
· Dark straw
· Light amber
· Amber
· Dark amber
· Red
The color of urine may be changed by the presence
of blood, drugs, or diagnostic dyes. Examples are:
· red or red-brown (smokey appearance), caused
by the presence of blood.
· yellow or brown (turning greenish with yellow
foam when shaken), caused by the presence of
bile.
· olive green to brown-black, caused by phenols
(an extremely poisonous compound, used as an
antimicrobial agent).
· milky white, caused by chyle. (Chyle, which
consists of lymph and droplets of triglyceride, is
a milky fluid taken up by lacteal vessels from the
food in the intestine during digestion.)
· dark orange, caused by Pyridium® (a topical
analgesic used in the treatment of urinary tract
infections).
· blue-green, caused by methylene blue (used as a
stain or dye for various diagnostic tests).
APPEARANCE.—Urine’s appearance may be
reported as clear, hazy, slightly cloudy, cloudy, or very
cloudy. Some physicians prefer the term “turbidity”
instead of “transparency,” but both terms are
acceptable.
Freshly passed urine is usually clear or
transparent. However, urine can appear cloudy when
substances such as blood, phosphates, crystals, pus, or
bacteria are present. A report of transparency is of
value only if the specimen is fresh. After standing, all
urine becomes cloudy because of decomposition, salts,
and the action of bacteria. Upon standing and cooling,
all urine specimens will develop a faint cloud
composed of mucus, leukocytes, and epithelial cells.
This cloud settles to the bottom of the specimen
container and is of no significance.
SPECIFIC GRAVITY.—The specific gravity of
the specimen is the weight of the specimen compared
to an equal volume of distilled water. The specific
gravity varies directly with the amount of solids
dissolved in the urine and normally ranges from 1.015
to 1.030 during a 24-hour period.
7-34
|
