Transcript Lab 14: Urinary System (Part II)

Lab 14: Urinary System (Part
II)
Dr. Kim Wilson
INTRODUCTION
• The analysis of urine has 2 purposes. One is to detect
body disturbances, such as endocrine or metabolic
abnormalities, in which the kidneys function normally but
excrete abnormal amounts of metabolic end products
specific for a particular disease. The second purpose is
to detect disease conditions within the kidneys or urinary
tract themselves that may adversely affect the urinary
system's ability to function efficiently in the maintenance
of fluid, electrolyte & acid-base balance. Urine may be
analyzed both physically & chemically using relatively
simple tests in order to check for abnormalities. In this
lab, a few of these physical & chemical tests will be
conducted on a sample of your own urine. For
reference, you should review information pertaining to
urinalysis in your textbook and in your lab manual (Unit
21).
PART 1: APPEARANCE AND PHYSICAL
PROPERTIES OF URINE
• INSTRUCTIONS:
• Obtain a clean specimen cup and collect a sample of
your urine. We won't be testing the specimen for the
presence of micro-organisms, however, obtain a
"midstream" specimen since it yields the best results.
• Pour part of your specimen (approx. 10 ml) into a test
tube and cap it. This portion will be allowed to set for 1
hour and then centrifuged in order to microscopically
examine its sediments. Use the remaining portion of
your specimen to perform the following physical and
chemical tests.
PART 1: APPEARANCE AND PHYSICAL
PROPERTIES OF URINE
• A. COLOR
• Freshly voided urine is often described as having a straw or amber
colored appearance. However, the normal color (which is due to the
presence of a pigment known as urochrome) may range
considerably from person to person. Concentrated urine, resulting
from loss of water in severe sweating, will be dark yellow; a light
amber yellow is more characteristic of dilute urine. Certain
deviations from the normal amber color may be the result of
disease, whereas other color changes may have no pathological
significance. For example, a brownish yellow or green color may be
the result of bile pigments, suggestive of liver disease. Likewise, a
smoky brown or reddish-brown colored urine usually indicates
disease, but may (on occasion) be the result of ingestion of plant
dyes found in beets or rhubarb.
• Record color on Results Sheet.
PART 1: APPEARANCE AND PHYSICAL
PROPERTIES OF URINE
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B. CLARITY (CLOUDINESS)
A freshly voided urine sample should be clear or transparent. If urine is
cloudy when voided or becomes cloudy after standing, the sample should
be checked (by microscopic examination & chemical tests) for the presence
of mucous, pus, bacteria, sperm, phosphate, or urate crystals.
Record clarity on Results Sheet.
C. ODOR
Normal, freshly voided urine has a "characteristic" odor which is believed to
be due to the presence of volatile acids. Urine that has been standing for a
long time at room temperature develops an ammonia-like odor which is due
to the decomposition of urea by bacteria in the specimen. The urine of
patients with diabetes mellitus may have an acetone odor due to the
presence of ketones. The urine of patients with urinary tract infections may
be foul-smelling, especially when the infecting organism is a coliform
bacillus. Abnormalities in urine odor may simply be due to the ingestion of
certain foods; for instance, garlic and asparagus can give urine
characteristic odors.
Record odor on Results Sheet.
PART 1: APPEARANCE AND PHYSICAL
PROPERTIES OF URINE
D. REACTION (pH)
The pH of urine is a measure of its hydrogen ion concentration. A pH below
7 indicates acid urine; a pH above 7 indicates alkaline urine. Freshly voided
urine from persons not on special diets is usually acid and has a pH of
approximately 6.0; however, normal kidneys are capable of producing urine
that can vary from a pH of 4.5 to a pH of 8. These variations seen in pH
may be related to diet, medication, or disease. For example, persons on
high protein diets produce a more acid urine whereas persons on diets high
in vegetables, milk or other dairy products produce an alkaline urine.
Persons with diabetes mellitus (uncontrolled) excrete urine containing large
amounts of acid whereas persons with urinary tract infections or persons
taking certain antibotics will excrete an alkaline urine.
INSTRUCTIONS:
1. Place a few ml's of fresh urine into a small cup. Dip a strip of pH test paper
into the sample 2 or 3 times.
2. Tap the pH paper on the edge of the cup to remove excess urine. Wait
one minute & record the pH on the Results Sheet.
PART 2: CHEMICAL COMPOSITION OF
URINE
• A. GLUCOSE
• Glucose is the sugar most commonly found in urine,
although other sugars such as lactose, fructose, or
galactose may also be found under certain conditions.
The presence of detectable amounts of glucose in urine
is known as glycosuria, and it may either occur in normal
or abnormal conditions. For example, glucose may
normally spill into the urine following consumption of a
heavy meal, especially one that contains large amounts
of carbohy-drates, or in conjunction with emotional
stress. The most common abnormal condition resulting
in glycosuria is diabetes mellitus. There are several
different tests available which check for the presence of
glucose in urine.
INSTRUCTIONS:
• Test # 1: Glucose Determination Using Clinitest Reagent Tablets.
• 1. Place 10 drops of water & 5 drops of urine in a test tube.
• 2. Add 1 Clinitest tablet. *Note: Handle Clinitest tablets with
extreme caution, using gloves. These tablets contain caustic
soda which is highly sensitive to moisture from air or water.
Excessive moisture may cause chemical burns or bottle
explosion.
• 3. Watch while a complete boiling reaction takes place.
(Boiling occurs because the concentrated sodium hydroxide in
the tablet generates heat.) Do not shake the test tube
during
the boiling or for the following 15 seconds after the
boiling
has stopped.
• 4. After the 15 seconds waiting period, gently shake the test
tube to mix the contents. Compare the color in the tube to
the standard color chart (for 5 drop method, not 2 drop
method).
• 5. Record results as Negative, Trace, 1+, 2+, 3+, or 4+ on the
Results Sheet.
Test # 2: Glucose Determination
Using Diastix
• 1. Pour a small amount of urine into a small cup.
• 2. Dip the reagent end of the strip in urine (do not touch
the reagent end with your hands). Remove
immediately.
• 3. While removing, draw the edge of the strip against
the rim of the cup to remove excess urine.
• 4. Compare the reagent side with the corresponding
color chart (on bottle) at exactly 30 seconds.
• 5. Record results on Results sheet.
Test # 3: Glucose Determination Using
Benedict's Test
• 1. Place 5 ml of Benedict's solution in a
test tube.
• 2. Add exactly 8 drops of urine and boil the
solution for 2 to 5 minutes.
• 3. If the solution remains blue, the test is
negative; green is recorded as +, yellow
as ++, orange as +++, and red as ++++.
• 4. Record results on Results sheet.
B. KETONES
• Normally the body completely metabolizes fats to carbon
dioxide and water. Whenever there is inadequate
carbohydrate intake or a defect in carbohydrate
metabolism, the body metabolizes increased amounts of
fatty acids. When this increase is large, fatty acid
utilization is incomplete and intermediate products
(Ketones) appear in the blood and are excreted in the
urine. Diabetes mellitus is the most important disorder in
which ketonuria (presence of ketones in urine) occurs.
As with glucose, there are several different tests
available which check for the presence of ketones.
INSTRUCTIONS:
Test # 1: Ketone Determination Using Acetest Reagent
Tablets
1. Place an Acetest tablet on a clean dry piece of paper
and put 1 drop of urine on the tablet.
2. At 30 seconds, compare the color formed with the color
chart.
The color will remain unchanged or cream-colored in a
negative test, but will vary from pink to purple, depending
on the amount of ketone bodies present, in a positive
test.
3. Record results on Results Sheet.
Test # 2: Ketone Determination
Using Ketostix Strips
1. Place a small amount of urine in a small cup.
2. Dip the reagent end of the strip in urine (do not touch
the reagent end with your hands). Remove
immediately.
3. While removing, draw the edge of the strip against the
rim of the cup to remove excess urine.
4. Exactly 15 seconds after removing the strip from the
specimen, compare the reagent side with the
corresponding color chart (on bottle). The color will
remain unchanged or appear cream colored (from
wetting) if negative; if positive, the color will vary from
pink to purple depending upon the amount of ketones
present.
5. Record results on Results Sheet.
C. PROTEIN
• Normally, between 40 and 80 mg of protein is
excreted daily, but as much as 100 - 150 mg per
day may be considered within normal limits.
Typically however, this normal protein isn't
detected in the urine. Proteinuria refers to an
increased amount of protein in the urine and is
one of the most important indicators of renal
disease; however, this condition may also
intermittently occur in the absence of
disease - usually as a result of strenous physical
exercise or severe emotional stress. Several
tests are available for measuring urinary protein.
INSTRUCTIONS:
Test #1: Protein Determination Using Albustix Reagent
Strips.
1. Place a small amount of urine in a small cup.
2. Dip the reagent end of the strip in the urine (do not touch
the reagent end with your hands). Remove immediately.
3. While removing, draw the edge of the strip against the
rim of the cup to remove excess urine.
4. Immediately after removing the strip from the urine,
compare the reagent side with the corresponding color
chart (on bottle).
5. Record results on Results Sheet.
D. BILE SALTS
Bile salts are an essential component of bile. Normally the majority these
substances are recycled in the body with only small amounts lost in urine (the
loss usually isn't detectable). Hay's Test for bile salts involves the addition of
sulfur to urine. Since bile salts lower the surface tension of the water in urine, if
bile salts are present, the sulfur will sink.
INSTRUCTIONS:
Hay's Test for Bile Salts in Urine
1. Place a small amount of urine in a small cup.
2. Sprinkle a little finely powdered sulfur on the surface of the urine. If the
sulfur sinks at once, bile salts are present in the amount of 0.01% or
more. If the sulfur sinks
only after gentle agitation, bile salts are
present in the
amount of 0.0025% or more. If the sulfur remains
floating
even after gentle shaking, bile salts are absent.
3. Record results on Results Sheet.
E. COMBINATION TESTS
INSTRUCTIONS:
Combistix Method (Determination of glucose, protein, & pH)
1. Place a small amount of urine in a small cup.
2. Dip the reagent end of the Combistix strip in urine ( do not touch the
reagent end with your hands). Remove immediately.
3. While removing, draw the edge of the strip against the rim of
the cup to remove excess urine.
4. The yellow part of the strip is the indicator for protein. It should be
read immediately and compared with the color chart (on bottle).
5. The aqua part of the strip is the test for glucose. This should be
read after 30 seconds by comparing the strip to the color chart (on
bottle).
6. The orange part of the strip is the pH indicator. It should be read
immediately and compared with the color chart (on bottle).
7. Record results on Results sheet.
PART 3: THE MICROSCOPIC EXAMINATION OF
SEDIMENT OBTAINED FROM
URINE
• INSTRUCTIONS:
• 1. Obtain the urine which has set in the
test tube for 1 hour.
• 2. Read the Discussion (below) and
complete the Procedure (below).
PROCEDURE
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1. Place 10 ml of fresh urine in a centrifuge tube and centrifuge for 5
minutes. (Precaution: Make certain the centrifuge is balanced with another
tube containing 10 ml of urine or water.)
2. Pour out all the urine possible (do this quickly without shaking the tube or
inverting it for more than a moment).
3. Add 2 drops of Sedi-Stain to the sediment in the tube. Thoroughly mix the
contents of the tube with the stain by tapping briskly on the bottom of the
tube with the index finger.
4. Transfer 1 drop of the stained sediment onto a clean glass slide.
5. Cover the drop of sediment with a cover glass and examine it under the
microscope using both low and high power objectives.
6. Identify as many of the substances in the sediment as possible by
comparing them with Figures 1 - 4 (see attached page - this handout), as
well as with the urine chart (on the materials table in the lab). Make a
drawing of your observations (white paper, high power). Be certain to
properly label your drawing.
7. Include your drawing in your lab report.
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ANSWER THE QUESTIONS FROM THE QUESTIONS SHEET.
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