Biology 142 (Winter 2008)
LABORATORY 9:
URINALYSIS
INTRODUCTION
The composition of blood depends on many factors. Three major factors are
cellular metabolism, diet and urinary output. The one million nephrons in the
kidney filter approximately 150 to 180 liters of blood plasma from the glomeruli
into the tubules. In addition to the filtration process, which occurs in the renal
corpuscle, the processes of tubular reabsorption and secretion occur between
the tubules and the capillaries.
The resultant urine produced contains
byproducts of metabolism and excess ions. The volume of urine produces
normally is 1.0 to 1.8 liters. A simple urinalysis including a routine and
microscopic analysis can be an extremely useful and simple diagnostic tool.
Freshly voided urine is generally clear and pale yellow to amber in colour.
Variations in colour indicate the relative concentration of solutes to water in the
urine but may be influenced by certain foods, vitamins and occasionally disease.
The pH may vary depending on diet and other factors which will be discussed but
is normally slightly acidic. Specific gravity is the relative weight of a specific
volume of liquid compared with an equal volume of distilled water. The specific
gravity (SG) of water is 1.000. Since urine contains dissolved solutes, it weighs
more than water and may vary dependent on many factors. Normal constituents
of urine include water, urea, creatinine, uric acid, and ions such as sodium,
potassium and phosphate. Smaller amounts of calcium, magnesium and
bicarbonate are also found normally in the urine. Abnormal amounts of any of
these constituents may indicate a pathological condition.
Objectives:
1.
2.
3.
4.
5.
6.
To describe the physical characteristics of normal urine and indicate the
normal pH and specific gravity ranges.
To discuss the substances that are normal urinary constituents.
To examine urine specimens and to conduct tests on these specimens.
To analyze the results of the tests and the possible significance of the
results.
To analyze urinalysis reports and to explain the implications and possible
causes of these urinary conditions.
To define terms related to common urinary conditions.
Materials:
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Test strips
Urine specimens (one of which will be your own)
Disposable gloves
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Biology 142 (Winter 2008)
Procedure:
Collecting urine sample
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obtain a sterile urine cup and lid
collect a midstream urine sample
at least 10 ml or urine is required
Urinalysis
Working with a lab partner, analyze your own urine sample and the 3 unknowns.
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examine the appearance of the specimens for colour and transparency
and degree of turbidity (cloudiness) and record your results in the tables.
obtain a test strip; dip the strip in the sample; remove and wait 20 sec
before recording results (colour developing after 2 min is not diagnostically
significant)
If any of the results are abnormal, identify the abnormal results and
discuss the implications and possible causes of these results
DATA SHEETS
Procedure/Test
Your urine
unknown
unknown
unknown
Colour
Turbidity
Specific Gravity
pH
Leukocytes
Nitrites
Protein
Glucose
Ketones
Urobilinogen
Bilirubin
Blood
Hemoglobin
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CONCLUSIONS:
Using the clinical terms defined on p13, summarize any abnormal results
detected in the unknown urine samples. Refer to the information on p 11 and 12,
and suggest what disorder these urinalyses indicate.
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Biology 142 (Winter 2008)
Centrifugation of your own urine sample
Procedure:
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using a disposable pipette, transfer 10 ml of your own urine to a plastic
centrifuge tube (don’t throw the pipette out yet).
the instructor will centrifuge the urine samples for several minutes.
retrieve your urine sample (note the sediment at the bottom of the
centrifuge tube).
using your pipette, remove the top 9.5 ml of urine, being careful not to
disturb the sediment at the bottom.
gently mix the sediment with the remaining 0.5 ml of urine
transfer a small drop of the mixture to a slide.
place a coverslip over the sample and view with a microscope at high
power.
NOTE: it is normal to find small crystals or small renal calculi and epithelial cells
in the urine; abnormal constituents are outlined on p 10 / 11
In the space below, sketch some of the things you see in your sample. Using the
charts provided, identify these constituents.
Figure title: ____________________________________ (magnify =
)
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Biology 142 (Winter 2008)
ABNORMAL URINARY CHARACTERISTICS AND CONSTITUENTS
Appearance of the specimen
The following are deviations from normal colour that may have pathological
implications:
Milky: may indicate presence of WBCs, bacteria or fat
Reddish-amber: may indicate urobilinogen which is produced in the
intestine by action of bacteria on bile or porphyrin which may indicate
evidence of liver disease, Addison’s or other conditions
Brownish-yellow or green: may indicate bile pigments
Red to smoky brown: may indicate blood and blood pigments
Transparency or turbidity
Cloudy urine: may be evidence of phosphates, urates, WBCs, bacteria,
epithelial cells or fat
Specific Gravity
The specific gravity of a 24-hour normal urine specimen will be between 1.015
and 1.025 (a random specimen may range from 1.002 to 1.030)
Less than 1.015 (24-hour specmin): may indicate excess fluid intake,
diabetes insipidis or chronic renal failure
More than 1.025 (24-hour specimen): may indicate limited fluid intake,
dehydration, fever, kidney inflammation
Abnormal constituents:
Glucose: may result from excessive carbohydrate intake or diabetes
mellitus
Albumin: may indicate abnormally increased permeability of the
glomerular membrane, kidney trauma, ingestion of heavy metals, bacterial
toxins, glomerulonephritis or hypertension
Ketone bodies: may indicate starvation or abnormal metabolic processes
such as excessive metabolism of fats or proteins in the body.
Nitrites: may indicate bacterial contamination / urinary trat infection (UTI)
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Biology 142 (Winter 2008)
Protein: may indicate glomerular damage or inflammation; may also arise
under conditions of physical stress or strenuous exercise
Red Blood Cells: may indicate irritation of the urinary tract organs by
calculi or physical trauma
Hemoglobin: may indicate hemolysis of red blood cells due to such
conditions as hemolytic anemias, transfusion reactions, burns or renal
disease
Bile pigments: may indicate liver pathology such as hepatitis or cirrhosis.
White blood cells: indicates inflammation of the urinary tract usually
caused by bacterial infection
Casts: usually indicate a pathological condition which may be due to
pyelonephritis, glomerulonephritis or other types of renal damage
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Biology 142 (Winter 2008)
LABORATORY 9 EXERCISE
1.
Identify the abnormal results in each of your specimens, and using your
notes, text and other references as necessary, discuss the implications
and possible causes of each of the abnormal results.
2.
Referring to your biology and nursing texts, medical dictionary and other
resources as necessary, briefly define the following urinary conditions, and
suggest possible cause(s) of each:
glycosuria
albuminuria
renal calculi
ketonuria
hematuria
pyuria
pyelonephritis
glomerulonephritis
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