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CHAPTER 16
URINALYSIS
PRETEST
True or False
1.
The urinary system functions to regulate the fluid
balance of the body.
2.
The functional unit of the kidney is the nephron.
3.
An excessive increase in urine output is termed
polyuria.
4.
A clean-catch midstream urine specimen is required
for a urine culture.
5.
Urinalysis consists of a physical, chemical, and
microscopic examination of urine.
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PRETEST, CONT.
True or False
6.
A urine specimen that is light yellow in color
indicates that bacteria are present in the specimen.
7.
The pH of most urine specimens is neutral.
8.
Blood may normally be present in the urine due to
menstruation.
9.
Hematuria refers to the presence of blood in the
urine.
10. HCG is a hormone that is present in the urine and
blood of a pregnant woman.
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Content Outline
Structure and Function of the Urinary
System
1. Function of urinary system
a. Regulate fluid and electrolyte balance of the
body
b. Remove wastes
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Structure and Function of the
Urinary System, cont.
2. Kidneys
a. Bean-shaped organs: 4½ inches long and 2
to 3 inches wide
b. Located in lumbar region
c. Produces urine
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Structure and Function of the
Urinary System, cont.
3. Ureters
a. 10 to 12 inches in length and ½ inch in
diameter
b. Propels urine into urinary bladder
•
By force of gravity and the peristaltic waves of
the ureters
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Structure and Function of the
Urinary System, cont.
4. Urinary bladder
a. Hollow, muscular sac
b. Holds approximately 500 ml of urine
c. Stores and expels urine
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Structure and Function of the
Urinary System, cont.
5. Urethra
a. Tube that extends from bladder to outside
b. Urinary meatus: external opening of urethra
c. Males: urethra transports urine and
reproductive secretions
d. Females: urethra transports urine only
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Urinary System
Modified from Applegate EJ: The anatomy and physiology learning system, ed 2, Philadelphia, 2000, Saunders.
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Nephron
6. Nephron
a. Each kidney composed of approximately 1
million smaller units known as nephrons
b. Nephron: Functional unit of the kidney
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Nephron, cont.
c. Function: Filters wastes from blood and
dilutes them with water to produce urine
d. Reabsorbs substances needed by the body:
•
Water
•
Glucose
•
Electrolytes
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Nephron
From Applegate EJ: The anatomy and physiology learning system, ed 2, Philadelphia, 2000, Saunders.
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Composition of Urine
1. Physiologic change in body caused by
disease:
a. Can create a disturbance in kidney function
•
Can be detected by examination of urine
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Composition of Urine, cont.
2. Urine composed of:
a. Water: 95%
b. Organic and inorganic waste products: 5%
c. Organic wastes: urea, uric acid, ammonia,
and creatinine
•
Urea present in greatest amounts
– Derived from breakdown of proteins
d. Inorganic wastes: chloride, sodium,
potassium, calcium, magnesium,
phosphate, sulfate
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Composition of Urine, cont.
2. Normal adult: excretes 750 to 2000 ml of
urine per day
a. Varies based on:
•
Amount of fluid consumed
•
Amount lost through other means (perspiration,
feces)
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Composition of Urine, cont.
3. Polyuria: excessive increase in urine
output
a. Caused by:
•
Excessive intake of fluids
•
Intake of fluids that contain caffeine (mild
diuretic)
•
Drugs (diuretics)
•
Pathological conditions (e.g., diabetes, renal
disease)
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Composition of Urine, cont.
4. Oliguria: decreased output of urine
a. Caused by:
• Decreased fluid intake·
• Vomiting
• Dehydration
• Diarrhea
• Profuse perspiration
• Kidney disease
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Terms Relating to the Urinary
System
1. Anuria: failure of the kidneys to produce
urine
2. Diuresis: secretion and passage of large
amounts of urine
3. Dysuria: difficult or painful urination
4. Frequency: the condition of having to
urinate often
5. Hematuria: blood present in urine
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Terms Relating to the Urinary
System, cont.
6. Nocturia: excessive (voluntary) urination
during the night
7. Nocturnal enuresis: the inability of the
patient to control urination at night
during sleep (bedwetting)
8. Pyuria: pus present in the urine
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Terms Relating to the Urinary
System, cont.
9. Retention: the inability to empty the
bladder
a. The urine is being produced normally but is
not being voided
10.Urgency: the immediate need to urinate
11.Urinary incontinence: the inability to
retain urine
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Collection of Urine
1. Advantages of urine testing
a. Urine is easily available
b. Does NOT require:
•
An invasive procedure
•
Use of special equipment
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Collection of Urine, cont.
2. To obtain accurate urine
test results:
a. Adhere to proper urine
collection procedures
•
Ensures collection of
proper specimen
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Guidelines for Urine Collection
1. Make sure to obtain an adequate volume
(usually 30 to 50 ml)
2. Properly label each specimen: avoids
mix-up of specimens
a. Patient's name
b. Date and time of collection
c. Type of specimen
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Guidelines for Urine Collection,
cont.
3. Record medications patient is taking on
laboratory requisition and in patient's
chart:
a. Some medications interfere with accuracy
of test results
4. Do not collect specimen during
menstruation:
a. May contaminate specimen with blood
•
Result in false-positive results on test for blood
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Guidelines for Urine Collection,
cont.
5. Difficult for some patients to void under
stress and anxiety
a. Be patient and relay understanding to
patient
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Guidelines for Urine Collection,
cont.
6. May be difficult to obtain from a child:
a. May need to use another collection method:
•
Urine collection bag
•
Suprapubic aspiration
•
Catheterization
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Urine Specimen Collection Methods
1. Type of test being
performed: often dictates
the collection method
a. Examples:
•
Pregnancy test: firstvoided morning specimen
•
Identification of a urinary
tract infection (UTI): cleancatch midstream collection
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Urine Specimen Collection Methods,
cont.
2. Most offices use disposable plastic
specimen containers
a. Available in different sizes
b. Have lids to:
•
Prevent spillage
•
Reduce contamination of the specimen
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Random Specimen
3. Random Specimen
a. Urine testing often performed on a freshly
voided specimen
b. MA instructs patient to void into clean, dry,
wide-mouthed container
c. Urine tested immediately
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First-Voided Morning Specimen
4. First-Voided Morning Specimen
a. Contains greatest concentration of
dissolved substances
b. Small amount of a substance detected more
easily
c. Instruct patient to collect first specimen of
the morning
•
Preserve in refrigerator
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First-Voided Morning Specimen,
cont.
d. Provide patient with specimen container
•
To prevent use of a container that harbors
contaminants
– Could cause inaccurate test results
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Clean-Catch Midstream Specimen
5. Clean-Catch Midstream Specimen
a. Microorganisms are NOT normally present
in:
•
Urinary bladder
•
Most of urethra
Modified from Applegate EJ: The anatomy and physiology learning system, ed 2, Philadelphia, 2000 Saunders.
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Clean-Catch Midstream Specimen,
cont.
b. Microorganisms are normally present in:
•
Distal urethra
•
Urinary meatus
Modified from Applegate EJ: The anatomy and physiology learning system, ed 2, Philadelphia, 2000 Saunders.
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Clean-Catch Midstream Specimen,
cont.
c. Clean-catch: required when urine is
cultured and examined for bacteria
d. Only microorganisms causing patient's
condition are desired in specimen
e. Ordered for:
•
Detection of a UTI
•
Evaluate effectiveness of drug therapy for a UTI
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Clean-Catch Midstream Specimen,
cont.
f. Clean-catch procedure:
•
Sterile container is used
•
To prevent contamination of specimen with
normal flora:
– Microorganisms are removed from urinary
meatus
1) By having patient cleanse meatus
– Microorganisms are flushed out of distal
urethra
2) By having patient void small amount into
toilet
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Clean-Catch Midstream Specimen,
cont.
g. Reduces possibility of having to obtain
urine specimen by:
• Bladder catheterization: Passing of a
sterile catheter through urethra into bladder
• Suprapubic aspiration of bladder:
Passing of a sterile needle through abdominal
wall into bladder
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Clean-Catch Midstream Specimen,
cont.
h. Guidelines
•
Collected by patient at office
•
MA provides instructions:
– Provide complete instructions:
1) To prevent contamination of specimen
with bacteria
2) Avoid patient having to collect another
specimen
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Clean-Catch Midstream Specimen,
cont.
•
Once collected: MA should immediately cap and
label container:
– Patient's name
– Date/time of collection
– Type of collection (clean-catch)
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Clean-Catch Midstream Specimen,
cont.
•
Test specimen immediately (or refrigerate)
– To ensure reliable test results
•
If sent to outside laboratory
– Complete laboratory request form
– Record in patient's chart: info on transport
of specimen to laboratory
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What Would You Do?
What Would You Not Do?
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What Would You Do?
What Would You Not Do?
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The 24-Hour Urine Specimen
1. Quantitative measurement of specific
urinary components
2. Greater accuracy of measurement than
with random specimen
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The 24-Hour Urine Specimen, cont.
3. Examples of substances measured:
a. Calcium
b. Creatinine
c. Lead
d. Potassium
e. Protein
f. Urea nitrogen
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The 24-Hour Urine Specimen, cont.
4. Often used to:
a. Diagnose the cause of kidney stone
formation
b. Assist in control and prevention of new
stone formation
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The 24-Hour Urine Specimen, cont.
5. Large container used (3000 ml)
6. Specimen must be kept refrigerated
a. To prevent changes in the quality of the
specimen
7. Some containers also contain a
preservative
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24-Hour Urine Specimen Container
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The 24-Hour Urine Specimen, cont.
8. MA should provide both written and
verbal instructions
a. Moderately limit fluid intake
b. Avoid alcohol for 24 hours before and
during collection
9. Physician may want patient to
discontinue certain medications for 1
week before test
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Analysis of Urine
1. Urinalysis: analysis of urine
2. Consists of:
a. Physical examination
b. Chemical examination
c. Microscopic examination
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Analysis of Urine, cont.
3. Deviation from normal on urinalysis
a. Assists in diagnosis and treatment of
pathologic conditions of:
•
Urinary system
•
Other body systems
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Analysis of Urine, cont.
4. May be performed:
a. As screening measure
•
Part of physical examination
b. Assist in diagnosis of a patient's condition
c. Evaluate effectiveness of therapy
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Analysis of Urine, cont.
5. Perform urinalysis on a fresh or
preserved specimen
a. If specimen cannot be examined with 1 hour
of voiding:
•
Preserve immediately in refrigerator
– Before testing:
1) Return to room temperature
2) Thoroughly mix specimen (rotate urine
container)
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Analysis of Urine, cont.
b. Changes that take place if specimen stands
out for more than 1 hour:
•
Bacteria in environment that get into specimen:
-Work on urea (acidic): converting it to ammonia
(alkaline)
1) Changes pH of urine: acid urine becomes
alkaline
2) May result in false-positive result on protein
test
•
Bacteria multiply resulting in:
– Cloudy specimen
– Increase in nitrite
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Analysis of Urine, cont.
•
If glucose present in specimen: amount
decreases
– Microorganisms use glucose for food
•
If any red or white blood cells present: they may
break down
•
Casts decompose after several hours
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Physical Examination of the Urine
1. For accurate evaluation of color and
appearance
a. Specimen must be in clear plastic or glass
container
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Physical Examination of the Urine,
cont.
2. Color
a. Ranges from almost colorless to dark
yellow
•
Dilute urine: lighter yellow
– Occurs as day progresses and more fluids
are consumed
•
Concentrated urine: darker yellow (e.g., firstvoided specimen)
– Occurs because fluid consumption is
decreased at night
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Physical Examination of the Urine,
cont.
b. Color due to yellow pigment: urochrome
•
From breakdown of hemoglobin
•
Color varies throughout the day
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Physical Examination of the Urine,
cont.
c. Classifications used to describe color:
•
Light yellow
•
Yellow
•
Dark yellow
•
Light amber
•
Amber
•
Dark amber
d. Color of urine:
•
Assists in determining additional tests that may
be necessary
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Color of Urine
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Physical Examination of the Urine,
cont.
e. Abnormal color may be due to:
•
Presence of hemoglobin or blood (reddish color)
•
Bile pigments (yellow-brown or greenish)
•
Fat droplets or pus (milky color)
•
Some foods and medications
f. Abnormal color: helps to determine
additional tests needed
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Physical Examination of the Urine,
cont.
3. Appearance
a. Fresh urine: usually clear or transparent
•
Becomes cloudy on standing out too long
b. Cloudiness in freshly voided specimen
•
Presence of bacteria, pus, blood, fat, yeast,
sperm, mucous threads, or fecal contaminants
•
Microscopic examination: performed on cloudy
specimens to determine cause
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Physical Examination of the Urine,
cont.
c. Classifications used to describe
appearance:
•
Clear
•
Slightly cloudy
•
Cloudy
•
Very cloudy
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Appearance of Urine
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Physical Examination of the Urine,
cont.
4. Odor
a. Freshly voided urine: slightly aromatic odor
b. Urine standing for long periods: ammonia
odor (due to breakdown of urea by bacteria)
c. Urine of diabetic patients may have fruity
odor: presence of ketones
d. Urine of patient with UTI: foul-smelling odor
e. Certain foods (e.g., asparagus causes a
musty smell)
f. Odor not generally used in diagnosis
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Specific Gravity
5. Specific gravity (SG)
a. Measures weight of urine as compared with
the weight of an equal volume of distilled
water
b. Indicates amount of dissolved substances
present in urine
c. Decreased SG:
•
Chronic renal insufficiency
•
Diabetes insipidus
•
Malignant hypertension
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Specific Gravity, cont.
d. Increased SG:
•
Adrenal insufficiency
•
Congestive heart failure
•
Hepatic disease
•
Diabetes mellitus
•
Conditions causing dehydration (e.g., fever,
vomiting, and diarrhea)
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Specific Gravity, cont.
e. Normal range for SG of urine: 1.003 to
1.030
•
Usually between 1.010 and 1.025
•
SG of distilled water: 1.000
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Specific Gravity, cont.
f. Dilute urine: lower SG (fewer dissolved
substances)
g. Concentrated urine: higher SG (more
dissolved substances)
•
Urine more concentrated in morning:
•
Increased amount of dissolved substances
h. Urine more dilute after fluid consumption
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Specific Gravity, cont.
i. Measurement of Specific
Gravity
•
Reagent strip method:
most common method used
to measure SG
– Color comparison
determination
– Strip dipped in urine
– Results compared with
color chart
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Specific Gravity, cont.
• Refractometer method
– Hand-held optical instrument
– Measures refractive index of urine: directly
correlates with SG of urine
– Results read from calibrated scale
– Advantage: only 1 or 2 drops of urine
required
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Chemical Examination of Urine
1. Purpose:
a. Indirect means of detecting abnormal
amounts of chemicals in the body
•
Substances present in excess (abnormal) amounts in
the blood are usually removed by urine
–
Example: glucose is normally present in blood
1) If exceeds a certain level: excess excreted in
urine
b. Detection of substances that do not
normally appear in the absence of disease
•
Example: blood and nitrite
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Chemical Examination of Urine,
cont.
2. Qualitative tests
a. Purpose:
-Indicates whether or not a
substance is present in
urine
-Provide approximate
indication of the amount
of the substance present
b. Usually involve use of
color chart
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Chemical Examination of Urine,
cont.
c. Results recorded in terms of:
•
Trace, 1+, 2+, 3+
•
Trace, small, moderate, large
•
Negative or positive
d. Useful as a screening test
•
Easy to perform
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Chemical Examination of Urine,
cont.
3. Quantitative tests
a. Indicate exact amount of chemical
substance present in the body
b. Results reported in measurable units:
•
Example: 14 mg/dL
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Chemical Examination of Urine,
cont.
4. Urine Testing Kits
a. Most frequently used in medical office for
chemical testing of urine
•
Advantages:
– Contain premeasured reagent
– Easy to perform
– Immediate results
b. Most are qualitative tests: positive result
indicates need for further testing
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Chemical Examination of Urine,
cont.
c. Most manufactured in
form of reagent strips
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Chemical Examination of Urine,
cont.
d. Rely on color change
for interpretation of
results
•
Color chart used to
make a visual
comparison
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Chemical Examination of Urine,
cont.
e. To ensure accurate and reliable test results
•
Carefully read and follow manufacturer's
instruction sheet
f. Test strips that contain more than one
reagent
•
May require different time intervals for reading
results
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Chemical Examination of Urine,
cont.
g. Certain medications may affect results:
listed in instructions
h. Expiration date must be checked before
using
•
Do not use if past expiration date
– Test results may be inaccurate
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Chemical Examination of Urine,
cont.
i. Should not be used if:
•
Color change has occurred on strip
•
Tested strip is a color that does not match chart
j. Light, heat, and moisture can affect strips
•
Store in cool, dry area
•
Tests are packaged in light-resistant container
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Chemical Examination of Urine,
cont.
k. Never transfer from original container to
another
•
Another container may contain moisture, dirt,
chemical
– Could affect test results
l. Recording test results
•
Indicate brand name of test that was used (e.g.,
Multistix 10SG)
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Types of Chemical Tests
1. pH
a. Unit that indicates acidity or alkalinity of a
solution
b. Range of pH scale: 0.00 to 14.0
•
Lower the number: greater the acidity
•
Higher the number: greater the alkalinity
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Types of Chemical Tests, cont.
c. pH readings:
•
Acid: Below 7
•
Alkaline: Above 7
•
Neutral: 7.0
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Types of Chemical Tests, cont.
d. Perform test on freshly voided urine
•
If urine allowed to stand out:
– Becomes more alkaline: urea is converted
to ammonia by bacteria
e. pH of urine: ranges from 4.6 to 8.0 (usually
around 6.0, which is acidic)
f. High reading on a fresh specimen: may
indicate bacterial infection of urinary tract
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Types of Chemical Tests, cont.
2. Glucose
a. Should not normally be present in urine
b. Glucose in the blood: filtered through
nephrons and reabsorbed into body
c. If glucose concentration in blood becomes
too high:
•
Kidneys unable to reabsorb all of glucose
– Results in glycosuria: glucose in the urine
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Types of Chemical Tests, cont.
•
Renal threshold is exceeded
– Renal threshold: Concentration at which a
substance in the blood not normally
excreted by the kidney begin to appear in
the urine
d. Renal threshold for glucose: generally
between 160 and 180 mg/dL
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Types of Chemical Tests, cont.
e. Diabetes: most common cause of
glycosuria
f. Alimentary glucosuria: patient has a low
renal threshold
•
Glucose may appear after consumption of large
quantities of sugar
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Types of Chemical Tests, cont.
3. Protein
a. Proteinuria: Presence of protein in the urine
•
Temporary increase may be caused by stress or
strenuous exercise
b. Conditions causing proteinuria
•
Glomerular filtration problems
•
Renal diseases
•
Bacterial infections of urinary tract
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Types of Chemical Tests, cont.
c. If proteinuria occurs:
•
Physician usually orders examination of
sediment
– To see what is causing the protein to be in
the patient's urine (e.g., bacteria)
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Types of Chemical Tests, cont.
4. Ketones
a. Three types of ketone bodies
•
Beta-hydroxybutyric acid
•
Acetoacetic acid
•
Acetone
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Types of Chemical Tests, cont.
b. Normal products of fat metabolism
c. Can be used by muscle tissue as a source
of energy
d. When more than normal amounts of fat are
metabolized:
•
Muscles cannot handle all of ketones that result
e. Ketosis: accumulation of large amounts of
ketone bodies in tissues and body fluids
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Types of Chemical Tests, cont.
f. Ketonuria: presence of ketone bodies in the
urine
•
Body rids itself of excess ketones by excreting
them in urine
g. Conditions causing ketonuria
•
Uncontrolled diabetes
•
Starvation
•
Diet composed almost entirely of fat
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Types of Chemical Tests, cont.
5. Bilirubin
a. Lifespan of red blood cell (RBC): 120 days
b. RBC: contains hemoglobin
•
Function of hemoglobin: transports oxygen in
the body
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Types of Chemical Tests, cont.
c. When a RBC breaks down: hemoglobin
breaks down
•
Releases bilirubin (vivid yellow pigment)
d. Bilirubin: normally transported to liver and
excreted with bile
•
Eventually leaves body through intestines
(feces)
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Types of Chemical Tests, cont.
e. With certain liver conditions:
•
Liver cannot accept bilirubin
•
Bilirubin transported to kidneys
– Excreted into urine: bilirubinuria
1) Causes urine to be yellow-brown or
greenish
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Types of Chemical Tests, cont.
f. Conditions causing bilirubinuria
•
Gallstones
•
Hepatitis
•
Cirrhosis of the liver
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Types of Chemical Tests, cont.
6. Urobilinogen
a. Conditions causing increase in urobilinogen
in urine:
•
Excessive hemolysis of red blood cells
•
Infectious hepatitis
•
Cirrhosis
•
Congestive heart failure (CHF)
•
Mononucleosis
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Types of Chemical Tests, cont.
7. Blood
a. Considered abnormal (unless due to
menstruation)
•
Hematuria: presence of blood in the urine
b. Conditions causing hematuria:
•
Injury
•
Cystitis
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Types of Chemical Tests, cont.
•
Tumors of bladder
•
Urethritis
•
Kidney stones
•
Certain kidney disorders
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Types of Chemical Tests, cont.
8. Nitrite
a. Indicates presence of a pathogen in urinary
tract (UTI)
b. Pathogens present in the urine in the
bladder:
•
Causes nitrate to convert to nitrite
– Nitrate: normally present in the urine
– Nitrite: normally absent in the urine
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Types of Chemical Tests, cont.
c. Perform on urine that has been in bladder 4
to 6 hours (first-voided specimen)
•
To ensure the pathogens have converted nitrate
to nitrite
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Types of Chemical Tests, cont.
d. Should not be performed on specimen that
has been standing out
•
Results in a false-positive result
– Caused by environmental bacterial
contamination of the specimen
e. Screening test: usually followed with
culture
•
To identify the pathogen
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Types of Chemical Tests, cont.
9. Leukocytes
a. Leukocyturia: presence of leukocytes in the
urine
•
Accompanies inflammation of kidneys and lower
urinary tract
b. Conditions causing leukocyturia
•
Acute and chronic pyelonephritis
•
Cystitis
•
Urethritis
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Types of Chemical Tests, cont.
c. Recommended specimen for women:
•
Clean-catch midstream collection
– Prevents contamination of specimen with
leukocytes from vaginal secretions
– Can cause false-positive test results
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What Would You Do?
What Would You Not Do?
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What Would You Do?
What Would You Not Do?
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Reagent Strips
1. Most common test used in medical
office to test urine
2. Disposable plastic strips: contain
reagent areas for testing chemicals in
urine
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Reagent Strips, cont.
3. Results provide physician with
information to assist in diagnosis of:
a. Kidney function conditions (e.g., kidney
stones)
b. Urinary tract infections
c. Carbohydrate metabolism conditions (e.g.,
diabetes mellitus)
d. Liver function conditions (e.g., hepatitis)
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Reagent Strips, cont.
4. Test results also provide physician with
information related to patient's:
a. Acid-base balance
b. Urine concentration
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Reagent Strips, cont.
5. Provide qualitative test results
a. Positive result: requires further testing
6. Number and type of reagent areas
depend on particular brand
7. Always read manufacturer's instructions
before performing test
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Reagent Strips, cont.
8. Guidelines for Reagent Strip Urine
Testing
a. Type of specimen: freshly voided
•
If not possible: refrigerate specimen
– Before testing
1) Allow to return to room temperature
2) Thoroughly mix specimen
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Reagent Strips, cont.
b. Type of collection:
•
Most designed to be used with a random
specimen
•
Certain tests require special collection
procedure:
– Nitrite test: First-voided morning specimen
– Leukocyte test: Clean-catch midstream
specimen
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Reagent Strips, cont.
c. Specimen container
•
Must be clean
– To prevent inaccurate
test results
•
Must be large enough
– To allow for complete
immersion of strip
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Reagent Strips, cont.
d. Interpretation of results:
•
Compare with color chart in good lighting
1) To obtain a good visual match
e. Storage of reagent strips: cool, dry area
with the cap tightly closed
•
Reagents on strips are sensitive to light, heat,
moisture
– Container includes a desiccant to absorb
moisture: do not remove
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Reagent Strips, cont.
7. Quality Control
a. Ensures reliability of test results
•
Determines if strips are reacting properly
•
Confirms that the test is being properly
performed and accurately interpreted
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Reagent Strips, cont.
b. Example: Chek-Stix
control checks reliability
of Multistix
•
Consists of a plastic strip
with seven synthetic
ingredients
•
Reconstituted in distilled
water for 30 minutes
– Ingredients dissolve in
the water
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Reagent Strips, cont.
•
Resulting solution is tested with a Multistix
reagent strip
- Using same procedure as a urine specimen
•
Expected values: outlined on a sheet
accompanying the control strips
- If expected values not obtained
1) Determine cause of problem and correct it
a) Outdated strips or control
b) Improper storage of strips or control
c) Error in technique
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Reagent Strips, cont.
c. Perform quality control
- When open a new bottle of strips
- Question of reliability with testing strips
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Reagent Strips, cont.
8. Urine analyzer
a. Performs chemical examination of urine
automatically
•
Uses reagent strips
b. Advantage
•
Quick and easy
•
Results are interpreted automatically
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Reagent Strips, cont.
c. Clinitek
•
Automatically reads Multistix
•
Results printed out
– Abnormal results are flagged
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Microscopic Examination of Urine
1. Urine sediment:
solid materials
contained in urine
a. Sediment sample
placed on a slide
by MA
b. Viewed under
microscope by
physician
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Microscopic Examination of Urine,
cont.
2. First-voided morning specimen
preferred
a. Contains more dissolved substances
•
Small amounts of abnormal substances: more
likely to be detected
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Microscopic Examination of Urine,
cont.
3. Red Blood Cells
a. Round, colorless, biconcave discs
b. Normal: 0 to 5 per high-power field
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Microscopic Examination of Urine,
cont.
c. More than 5 per high-power field: may
indicate bleeding along urinary tract
d. Concentrated urine: causes RBCs to
become shrunken or crenated
e. Dilute urine: causes RBCs to swell and
hemolyze
•
Will not be seen under microscope
– Will still show a positive on reagent strip test
(for blood)
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Red Blood Cells
Courtesy Bayer Corporation, Elkhart, Ind.
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Microscopic Examination of Urine,
cont.
4. White Blood Cells
a. Round, granular, with a nucleus
b. Approximately 1.5 times larger than RBC
c. Normal: 0 to 8 per high-power field
d. More than 8 per high-power field: may
indicate inflammation of genitourinary tract
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White Blood Cells
Courtesy Bayer Corporation, Elkhart, Ind.
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Microscopic Examination of Urine,
cont.
5. Epithelial Cells
a. Most structures making up urinary system:
composed of several layers of epithelial
cells
b. Outer layer: constantly being sloughed off
•
Replaced by cells underneath
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Microscopic Examination of Urine,
cont.
c. Squamous epithelial cells: large, clear, flat
cells with irregular shape
•
Contain small nucleus
•
Come from urethra, bladder, vagina
•
Normally present in small amounts in urine
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Squamous Epithelial Cells
Courtesy Bayer Corporation, Elkhart, Ind.
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Microscopic Examination of Urine,
cont.
d. Renal epithelial
cells: round with
large nucleus
•
Come from
deeper layers of
urinary tract
•
Presence in
urine is
abnormal
Courtesy Bayer Corporation, Elkhart, Ind.
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Microscopic Examination of Urine,
cont.
6. Casts
a. Cylindrical structures: formed in lumen of
nephron tubules
b. Materials in tubules harden and are flushed
out: appear in urine as casts
c. Generally indicate diseased condition
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Microscopic Examination of Urine,
cont.
d. Named
according to
what they
contain
• Hyaline casts:
pale, colorless
cylinders with
rounded edges
– Vary in size
From Stepp CA, Woods M: Laboratory procedures for medical office
personnel, Philadelphia, 1998, Saunders.
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Microscopic Examination of Urine,
cont.
• Granular casts:
hyaline casts that
contain granules
From Stepp CA, Woods M: Laboratory procedures for medical office
personnel, Philadelphia, 1998, Saunders.
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Microscopic Examination of Urine,
cont.
• Fatty casts:
hyaline casts
that contain fat
droplets
From Henry JB: Clinical diagnosis and management by laboratory methods,
ed 20, Philadelphia, 2001, Saunders.
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Microscopic Examination of Urine,
cont.
• Waxy casts: light
yellowish with
serrated edges
– Appear to be
made of wax
From Stepp CA, Woods M: Laboratory procedures for medical office personnel,
Philadelphia, 1998, Saunders.
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Microscopic Examination of Urine,
cont.
e. Cellular Casts:
hyaline casts that
contain organized
structures
•
Named for what
they contain
– RBC casts
From Stepp CA, Woods M: Laboratory procedures for medical office personnel,
Philadelphia, 1998, Saunders.
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Microscopic Examination of Urine,
cont.
– White
blood cell
(WBC)
casts
Courtesy Bayer Corporation, Diagnostics Division, Elkhart, Ind.
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Microscopic Examination of Urine,
cont.
– Epithelial
cell casts
From Henry JB: Clinical diagnosis and management by laboratory methods,
ed 20, Philadelphia, 2001, Saunders.
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Microscopic Examination of Urine,
cont.
7. Crystals
a. Variety may be found in urine
b. Type and number vary with urine pH
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Microscopic Examination of Urine,
cont.
c. Abnormal crystals:
•
Leucine
•
Tyrosine
•
Cystine
•
Cholesterol
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Microscopic Examination of Urine,
cont.
d. Crystals that commonly appear in acidic
urine
•
Amorphous urates
•
Uric acid
•
Calcium oxalate
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Microscopic Examination of Urine,
cont.
e. Crystals that commonly appear in alkaline
urine
•
Amorphous phosphate
•
Triple phosphate
•
Calcium phosphate
•
Ammonium urate
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Microscopic Examination of Urine,
cont.
8. Miscellaneous
Structures
a. Mucous threads:
normally present
in small amounts
in urine
•
Long, wavy,
threadlike
structures with
pointed ends
From Stepp CA, Woods M: Laboratory procedures for medical office personnel,
Philadelphia, 1998, Saunders.
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Microscopic Examination of Urine,
cont.
b. Bacteria: rod shaped or round
•
Should not normally be present
•
Presence of more than a few:
– May indicate contamination of specimen
during collection
– UTI
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Bacteria
Courtesy Bayer Corporation, Diagnostics Division, Elkhart, Ind.
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Microscopic Examination of Urine,
cont.
c. Yeast cells
•
Smooth, refractile bodies with oval shape
•
Small buds project from cells
•
In females:
– Usually vaginal contaminant caused by
Candida albicans (yeast infection)
•
May also be present in patients with diabetes
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Yeast
Courtesy Bayer Corporation, Diagnostics Division, Elkhart, Ind.
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Microscopic Examination of Urine,
cont.
d. Parasites
•
May be present as a
contaminate from
fecal or vaginal
material
•
Trichomonas
vaginalis: parasite
that causes
trichomoniasis
vaginitis
Courtesy Bayer Corporation, Diagnostics Division, Elkhart, Ind.
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Microscopic Examination of Urine,
cont.
e. Spermatozoa
•
May be present in
men or women
after intercourse
•
Have round heads,
long, slender,
hairlike tails
Courtesy Bayer Corporation, Diagnostics Division, Elkhart, Ind.
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Rapid Urine Cultures
1. Assist in:
a. Diagnosis of UTI
b. Assessment of effectiveness of antibiotic
therapy for UTI
2. Used in medical office: to culture a urine
specimen
a. Provides more immediate results
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Rapid Urine Cultures, cont.
3. Brand names
a. Uricult
b. Uricheck
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Rapid Urine Cultures, cont.
4. Consists of slide
attached to a screw cap
a. Each side of slide
coated with agar
medium:
•
Suitable for growth of
urinary bacteria
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Rapid Urine Cultures, cont.
5. Do not use:
a. If agar is dehydrated
b. If mold or bacterial growth present
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Rapid Urine Cultures, cont.
6. Slide suspended in clean plastic vial:
protects it from contaminants
7. Recommended urine specimen: cleancatch midstream
a. Collected after urine has been in bladder
for 4 to 6 hours
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Rapid Urine Cultures, cont.
b. Slide is dipped into the
urine specimen
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Rapid Urine Cultures, cont.
c. Slide is incubated
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Rapid Urine Cultures, cont.
d. Slide is
compared with a
reference chart
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Urine Pregnancy Testing
1. Purpose
a. To determine if a woman is pregnant
b. Before certain medications are given or
procedures performed that may cause
injury to a fetus
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Urine Pregnancy Testing, cont.
2. Immunologic tests often used in office
a. Test results rely on the presence of human
chorionic gonadotropin (HCG)
3. Concentrated urine specimen required
(first-voided morning)
4. HCG: produces positive result
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HCG
1. Produced by developing fertilized egg
a. Small amounts secreted into urine and
blood
2. Immediately after conception and
implantation: level of HCG rises rapidly
a. Can detect pregnancy with a serum
pregnancy test
- As early as 6 days before the first missed
period
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HCG, cont.
3. Highest level: occurs 8 weeks after
conception
a. After this time: HCG declines
4. 72 hours after delivery: HCG disappears
entirely
5. Pregnancy tests more sensitive first
trimester
a. May even show a negative reaction during
second and third trimester
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Urine Pregnancy Testing Methods
1. Two main types
a. Immunoassay enzyme test
b. Agglutination test
2. Positive and negative reactions: causes
a visible reaction
3. Available in kits: are 97% accurate
a. Low occurrence of false positive results
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Urine Pregnancy Testing Methods,
cont.
4. Agglutination Tests
a. Sometimes used in medical office
•
Absence of agglutination: positive reaction
•
Presence of agglutination: negative reaction
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Urine Pregnancy Testing Methods,
cont.
5. Immunoassay tests
a. Brand names
•
QuickVue
•
Clearview
•
OSOM
•
ICON
b. Early prediction pregnancy tests
•
May be able to detect pregnancy
-1 week after implantation (4 to 5 days before first
missed period)
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Urine Pregnancy Testing Methods,
cont.
c. Take approximately
5 minutes to
perform
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Urine Pregnancy Testing Methods,
cont.
d. Results observed
as a color change
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Guidelines for Urine Pregnancy
Testing
1. Use clean, disposable urine containers
2. Use first-voided morning specimen:
contains highest concentration of HCG
3. Specific gravity should be determined
before test
a. Less than 1.010: too dilute for testing
•
Could cause a false-negative result
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Guidelines for Urine Pregnancy
Testing, cont.
4. Urine specimen should be at room
temperature
5. Kit should be stored according to
manufacturer's instructions
6. Kit past expiration date: should not be
used
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Serum Pregnancy Test
1. Radioimmunoassay (RIA) for HCG: used to
detect HCG in serum of blood
2. More sensitive than urine testing
a. Can detect pregnancy earlier with more accuracy
3. Can detect pregnancy at approximately eighth
day after fertilization (6 days before first missed
period)
4. Uses radioisotope technique
a. Capable of detecting minute amounts of HCG in the
blood
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Serum Pregnancy Test, cont.
5. Use
a. Diagnose abnormalities (ectopic
pregnancy)
b. Follow course of early pregnancy:
•
When abnormalities of embryonic development
are suspected
c. Provide early diagnosis of pregnancy in
high-risk patients
•
Example: Patient with diabetes mellitus
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What Would You Do?
What Would You Not Do?
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What Would You Do?
What Would You Not Do?
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POSTTEST
True or False
1.
2.
3.
4.
5.
The external opening of the urethra is known as the
external os.
A normal adult excretes approximately 250 ml of
urine each day.
Vomiting can result in oliguria.
The distal urethra normally contains
microorganisms.
A 24-hour urine specimen may be collected to assist
in the diagnosis of a UTI.
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POSTTEST, CONT.
True or False
6.
If a urine specimen is allowed to stand for more than
1 hour at room temperature, the pH becomes more
acidic.
7. If a freshly voided specimen is cloudy, this may mean
that a urinary tract infection is present.
8. The normal specific gravity of urine ranges from
1.003 to 1.030.
9. Dysuria is the inability to control urination at night.
10. Casts are formed in the urinary bladder.
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174