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Bonewit: Clinical Procedures for Medical Assistants, 8th Edition
Chapter 16: Urinalysis
Content Outline
Structure and Function of the Urinary System
1. Function of the urinary system
a. Regulate the fluid and electrolyte balance of the body
b. Remove wastes
2. Kidneys
a. Bean-shaped organs: 4.5 inches long and 2 to 3 inches wide
b. Located in the lumbar region
c. Produces urine
3. Ureters
a. 10 to 12 inches in length and 1 2 inch in diameter
b. Propels urine into the urinary bladder
 By force of gravity and the peristaltic waves of the ureters
4. Urinary bladder
a. Hollow, muscular sac
b. Holds approximately 500 ml of urine
c. Stores and expels urine
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
6. Nephron
a. Each kidney is composed of approximately 1 million smaller units known as
nephrons
b. Functional unit of the kidney
c. Function: filters wastes from blood and dilutes them with water to produce urine
d. Reabsorbs substances needed by the body
 Water
 Glucose
 Electrolytes
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
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
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- Derived from the breakdown of proteins
d. Inorganic wastes: chloride, sodium, potassium, calcium, magnesium, phosphate,
sulfate
3. 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)
4. Polyuria: excessive increase in urine output
a. Caused by
 Excessive intake of fluids
 Intake of fluids that contain caffeine (mild diuretic)
 Drugs (diuretics)
 Pathologic conditions (e.g., diabetes, renal disease)
5. Oliguria: decreased output of urine
a. Less than 400 ml in 24 hours
b. Caused by
 Decreased fluid intake
 Dehydration
 Profuse perspiration
 Vomiting
 Diarrhea
 Kidney disease
6. Micturition: normal act of voiding urine
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 the urine
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
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
Collection of Urine
1. Advantages of urine testing
a. Urine is readily available
b. Does not require
 An invasive procedure
 Use of special equipment
2. To obtain accurate urine test results
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a. Adhere to proper urine collection procedures
 Ensures collection of proper specimen
Guidelines for Urine Collection
1. Obtain an adequate volume (usually 30 to 50 ml)
2. Properly label each specimen: avoids mix-up of specimens
a. Patient’s name and DOB
b. Date and time of collection
c. Type of specimen (i.e., urine)
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 the specimen during menstruation
a. May contaminate specimen with blood
 Result in false-positive results on test for blood
5. Difficult for some patients to void under stress and anxiety
a. Be patient and relay understanding to patient
6. May be difficult to obtain from a child
a. May need to use another collection method
 Urine collection bag
 Suprapubic aspiration
 Catheterization
Urine Specimen Collection Methods
1. Type of test being performed: often dictates the collection method
a. Examples
 Pregnancy test: first-voided morning specimen
 Identification of a UTI: clean-catch midstream collection
2. Most offices use disposable plastic specimen containers
a. Available in different sizes
b. Have lids to:
 Prevent spillage
 Reduce contamination of the specimen
3. Random specimen
a. Urine testing often performed on a freshly voided specimen
b. MA instructs patient to void into a clean, dry, wide-mouthed container
c. Urine tested immediately
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
d. Provide patient with specimen container
 To prevent use of a container that harbors contaminants
- Could cause inaccurate test results
5. Clean-catch midstream specimen
a. Microorganisms are not normally present in
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Urinary bladder
Most of the urethra
b. Microorganisms are normally present in
 Distal urethra
 Urinary meatus
c. Clean-catch: required when urine is cultured and examined for bacteria
 To prevent contamination of the specimen with normally present
microorganisms
d. Only microorganisms causing patient’s condition are desired in the specimen
e. Ordered for
 Detection of a UTI
 Evaluate effectiveness of drug therapy for a UTI
f. Clean-catch procedure
 Sterile container is used
 To prevent contamination of the specimen with normal flora
- Microorganisms are removed from the urinary meatus
(1) By having patient cleanse area surrounding the urinary meatus
- Microorganisms are flushed out of the distal urethra
(1) By having patient void small amount into toilet
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
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
 When collected: MA should immediately cap and label the container
- Patient’s name and DOB
- Date and time of collection
- Type of collection (clean-catch)
 Test specimen immediately (or refrigerate)
- To ensure reliable test results
 If sent to outside laboratory
- Complete laboratory request form
- Record in patient’s chart: information on transport of specimen to
laboratory
Twenty-Four-Hour Urine Specimen
1. Quantitative measurement of specific urinary components
2. Greater accuracy of measurement than with a random specimen
3. Examples of substances measured
a. Calcium
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b. Cortisol
c. Lead
d. Potassium
e. Protein
f. Urea nitrogen
4. Often used to
a. Diagnose the cause of kidney stone formation
b. Assist in control and prevention of new stone formation
5. Large container used (3000 ml)
a. Used to store urine collected over 24 hours
6. To prevent changes in the quality of the specimen
a. Specimen must be kept refrigerated
b. Or placed in an ice chest
7. Some containers also contain a preservative
a. Maintains quality of specimen
b. Hazardous chemical warning label should be attached to container
c. Instruct patient not to discard or touch preservative
8. Patient also provided with container to collect specimen
a. Female: urine “hat”
 Placed over commode under toilet seat
b. Male: collection cup
 After collection: urine placed into the large specimen container
c. Makes collection easier and safer
 If patient voids directly into container with preservative
- Could splash onto patient’s skin
(1) Resulting in a chemical burn
9. MA should provide written and verbal instructions
a. Drink normal amount of fluid during the collection period
b. Avoid alcohol for 24 hours before and during the collection period
c. Choose 24-hour period when patient will be at home
 So urine will not have to be transported
d. Do not perform during menstruation
10. Physician may want patient to discontinue certain medications for 1 week before the
test
Analysis of Urine
1. Urinalysis: analysis of urine
2. Consists of
a. Physical examination
b. Chemical examination
c. Microscopic examination
3. Deviation from normal on urinalysis
a. Assists in diagnosis and treatment of pathologic conditions of
 Urinary system
 Other body systems
4. May be performed
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a. As screening measure
 Part of physical examination
b. Assist in the diagnosis of a patient’s condition
c. Evaluate effectiveness of therapy
 After treatment has been initiated
5. Perform urinalysis on a fresh or preserved specimen
a. If specimen cannot be examined within 1 hour of voiding
 Preserve immediately in refrigerator
- Before testing
(1) Return to room temperature
(2) Thoroughly mix specimen (rotate urine container)
b. Changes that occur if specimen stands out for more than 1 hour
 Bacteria in environment that get into specimen
- Work on urea: 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
 If glucose is present in specimen: amount decreases
- Microorganisms use glucose for food
 If any red or white blood cells are present: they may break down
 Casts decompose after several hours
Physical Examination of Urine
1. For accurate evaluation of color and appearance
a. Specimen must be in clear plastic or glass container
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., first-voided specimen)
- Occurs because fluid consumption is decreased at night
b. Color due to yellow pigment: urochrome
 From breakdown of hemoglobin
 Color varies among different shades of yellow throughout the day
c. Classifications used to describe color
 Light yellow
 Yellow
 Dark yellow
 Light amber
 Amber
 Dark amber
d. Color of urine specimen
 Assists in determining additional tests that may be necessary
e. Abnormal color may be due to
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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 if additional tests are needed
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
- Cloudiness resulting from bacteria may be caused by a UTI
c. Classifications used to describe appearance
 Clear
 Slightly cloudy
 Cloudy
 Very cloudy
4. Odor
a. Freshly voided urine: slightly aromatic odor
b. Urine standing for long periods: ammonia odor
 As a result of breakdown of urea by bacteria
c. Urine of diabetic patients may have fruity odor: presence of ketone
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 of the patient’s condition
5. Specific gravity (SG)
a. Measures weight of urine compared with weight of an equal volume of distilled
water
b. Indicates amount of dissolved substances present in urine
c. Provides information on ability of the kidney to dilute or concentrate the urine
d. Decreased SG
 Chronic renal insufficiency
 Diabetes insipidus
 Malignant hypertension
e. Increased SG
 Adrenal insufficiency
 Congestive heart failure
 Hepatic disease
 Diabetes mellitus with glycosuria
 Conditions causing dehydration (e.g., fever, vomiting, and diarrhea)
f. Normal range for SG of urine: 1.003 to 1.030
 Usually 1.010 to 1.025
 SG of distilled water: 1.000
g. Dilute urine: lower SG (fewer dissolved substances)
h. Concentrated urine: higher SG (more dissolved substances)
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Urine is more concentrated in the morning:
- Increased amount of dissolved substances
i. Urine more dilute after fluid consumption
j. Measurement of SG
 Reagent strip method: most common method used to measure SG
- Color comparison determination
- Strip dipped in urine
- Results compared with color chart
Chemical Examination of Urine
1. Used to assist in the diagnosis of:
a. Kidney function
b. Urinary tract infections
c. Carbohydrate metabolism (diabetes mellitus)
d. Liver function
2. Substances present in excess (abnormal) amounts in the blood
a. Are usually removed by urine
 Example: glucose is normally present in blood
- If it exceeds a certain level: excess excreted in urine
3. Indirect means of detecting abnormal amounts of chemicals in the body
4. Detection of substances that do not normally appear in the absence of disease
 Example: blood and nitrite
5. Chemical tests that are routinely performed:
a. pH
b. Glucose
c. Protein
d. Ketone
6. Other tests that may be performed:
a. Blood
b. Bilirubin
c. Urobilinogen
d. Nitrite
e. Leukocytes
7. Qualitative test results
a. Purpose
 Indicate whether a substance is present in urine
 Provide approximate indication of amount of substance present
b. Interpretation of results
 Usually involves use of color comparison chart
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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8. Quantitative test results
a. Indicate exact amount of chemical substance present in the body
b. Results reported in measurable units
 Example: 14 mg/dl
c. Obtaining quantitative result on urine specimen
 Usually involves use of complex equipment and testing procedures
 Not usually performed in the medical office
9. Urine testing kits
a. Most frequently used in the medical office for chemical testing of urine
 Advantages
- Contain premeasured reagent
- Easy to perform
- Provide immediate results
b. Most are qualitative test results: positive result indicates need for further testing
c. Most manufactured in the form of reagent strips
d. Rely on color change for interpretation of results
 Color chart used to make a visual comparison
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
g. Certain medications may affect results: listed in instructions
h. Expiration date must be checked before using
 Do not use if past the expiration date
- Test results may be inaccurate
i. Should not be used if
 Color change has occurred on strip
 Tested strip is a color that does not match the chart
j. Light, heat, and moisture can affect strips
 Store in cool, dry area
 Tests are packaged in a light-resistant container
k. Never transfer from original container to another
 Another container may contain moisture, dirt, or chemicals
- Could affect test results
l. Recording test results
 Indicate brand name of test that was used (e.g., Multistix 10SG)
Types of Chemical Tests
1. pH
a. Unit that indicates acidity or alkalinity of a solution
b. Range of pH scale: 0.0 to 14.0
 Lower the number: greater the acidity
 Higher the number: greater the alkalinity
c. pH readings
 Neutral: 7.0
 Acid: below 7
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Alkaline: above 7
d. Perform test on freshly voided urine
 If urine is 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 (acidic)
f. High reading on a fresh specimen (i.e., alkaline urine):
 May indicate bacterial infection of urinary tract
2. Glucose
a. Should not normally be present in urine
b. Glucose in the blood: filtered through nephrons and reabsorbed into the body
c. If glucose concentration in blood becomes too high: renal threshold is exceeded
 Kidneys unable to reabsorb all of glucose back into the blood
- Results in glycosuria: glucose in the urine
 Renal threshold is exceeded
- Renal threshold: concentration at which a substance in the blood not
normally excreted by the kidney begins to appear in the urine
d. Renal threshold for glucose: generally 160 to 180 mg/dl
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
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
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)
4. Ketones
a. Three types of ketone bodies
 β-Hydroxybutyric acid
 Acetoacetic acid
 Acetone
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 the ketones that result
e. Ketosis: accumulation of large amounts of ketone bodies in tissues and body
fluids
f. Ketonuria: presence of ketone bodies in the urine
 Body rids itself of excess ketones by excreting them in urine
g. Conditions causing ketonuria
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Uncontrolled diabetes
Starvation
Diet composed almost entirely of fat
5. Bilirubin
a. Life span of RBC: 120 days
b. RBC: contains hemoglobin
 Function of hemoglobin: transports oxygen in the body
c. When RBC breaks down: hemoglobin breaks down
 Releases bilirubin (vivid yellow pigment)
d. Bilirubin: normally transported to liver and excreted with bile
 Eventually leaves the body through the intestines (feces)
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
f. Conditions causing bilirubinuria
 Gallstones
 Hepatitis
 Cirrhosis of the liver
6. Urobilinogen
a. Conditions causing increase in urobilinogen in the urine
 Excessive hemolysis of red blood cells
 Infectious hepatitis
 Cirrhosis
 CHF
 Mononucleosis
7. Blood
a. Considered abnormal (unless resulting from menstruation)
 Hematuria: presence of blood in the urine
b. Conditions causing hematuria
 Injury
 Cystitis
 Tumors of the bladder
 Urethritis
 Kidney stones
 Certain kidney disorders
8. Nitrite
a. Indicates presence of a pathogen in the 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
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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d. Should not be performed on specimen that has been standing out
 Results in a false-positive result
- Due to environmental bacteria contamination of the specimen
e. Screening test: usually followed with culture
 To identify the pathogen
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
c. Recommended specimen for women
 Clean-catch midstream collection
- Prevents contamination of specimen with leukocytes from vaginal
secretions
- Can cause false-positive test results
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
3. Results provide physician with information to assist in the diagnosis of:
a. Kidney function conditions (e.g., kidney stones)
b. UTI
c. Carbohydrate metabolism conditions (e.g., diabetes mellitus)
d. Liver function conditions (e.g., hepatitis)
4. Test results also provide physician with information related to:
a. Acid-base balance of the body
b. Urine concentration
5. Provide qualitative test results
a. Positive result: requires further testing
6. Number and type of reagent areas depend on particular brand of strips used
7. Always read manufacturer’s instructions before performing the test
8. Guidelines for reagent strip urine testing
a. Preferred type of specimen: freshly voided and thoroughly mixed
 If not possible: refrigerate specimen
- Before testing
(1) Allow to return to room temperature
(2) Thoroughly mix specimen
b. Type of collection
 Most designed to be used with a random specimen
 Certain tests require a special collection procedure
- Nitrite test: first-voided morning specimen
- Leukocyte test: clean-catch midstream specimen
c. Specimen container
 Must be clean
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- To prevent inaccurate test results
 Must be large enough
- To allow for complete immersion of strip
d. Time intervals
 Read results at exact time intervals
- Specified on color chart
 Do not read any test results after 2 minutes
e. Interpretation of results
 Compare with color chart in good lighting
- To obtain a good visual match
f. Storage of reagent strips: cool, dry area with the cap tightly closed
 Reagents on strips are sensitive to light, heat, and moisture
- Container includes a desiccant to absorb moisture: do not remove
 Store at a temperature between 59°F (15°C) and 86°F (30°C)
- Do not store in refrigerator or freezer
 Tan-to-brown discoloration or darkening on reagent areas
- Indicates deterioration of strips
- Do not use strips: test results would be inaccurate
9. Quality control testing
a. Ensures reliability of test results
 Determines if strips are reacting properly
 Confirms that the test is being properly performed and accurately interpreted
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
 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
- Record control test results in a quality control log
- If expected values are 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
c. Perform quality control
 When opening a new bottle of strips
 Question of reliability with testing strips
10. Urine analyzer
a. Performs chemical examination of urine automatically
 Uses reagent strips
b. Advantage
 Quick and easy
 Results are interpreted automatically
c. Clinitek analyzer
 Automatically reads Multistix
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Results printed out
- Abnormal results are flagged
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
c. Helps clarify results of the physical and chemical examination
2. First-voided morning specimen preferred: more concentrated
a. Contains more dissolved substances
 Small amounts of abnormal substances: more likely to be detected
3. Important to use a fresh specimen
a. Changes occur if specimen is left standing out
 Affects reliability of test results
4. MA responsible for preparing urine specimen
a. For microscopic examination by physician
5. Red blood cells
a. Round, colorless, biconcave discs
b. Normal: 0 to 5 per high-power field
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
 Cannot be seen under a microscope
- Still show a positive result on reagent strip test (for blood)
6. White blood cells
a. Round, granular, and have a nucleus
b. Approximately 1.5 times larger than RBCs
c. Normal: 0 to 8 per high-power field
d. More than 8 per high-power field: may indicate inflammation of genitourinary
tract
7. 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
c. Squamous epithelial cells: large, clear, flat cells with irregular shape
 Contain small nucleus
 Come from urethra, bladder, or vagina
 Normally present in small amounts in urine
d. Renal epithelial cells: round with large nucleus
 Come from deeper layers of the urinary tract
 Presence in urine is abnormal
8. 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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d. Named according to what they contain
 Hyaline casts: pale, colorless cylinders with rounded edges
- Vary in size
 Granular casts: hyaline casts that contain granules
 Fatty casts: hyaline casts that contain fat droplets
 Waxy casts: light yellowish with serrated edges
- Appear to be made of wax
e. Cellular casts: hyaline casts that contain organized structures
 Named for what they contain
- RBC casts
- WBC casts
- Epithelial casts
- Bacterial casts
9. Crystals
a. Variety may be found in urine
b. Type and number vary with urine pH
c. Abnormal crystals
 Leucine
 Tyrosine
 Cystine
 Cholesterol
d. Commonly appear in acidic urine
 Amorphous urates
 Uric acid
 Calcium oxalate
e. Commonly appear in alkaline urine
 Amorphous phosphate
 Triple phosphate
 Calcium phosphate
 Ammonium urate
10. Miscellaneous structures
a. Mucous threads: normally present in small amounts in urine
 Long, wavy, threadlike structures with pointed ends
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
c. Yeast cells
 Smooth, refractile bodies with an oval shape
 Small buds project from cells
 In females
- Usually vaginal contaminant caused by Candida albicans (yeast
infection)
 Also may be present in patients with diabetes
d. Parasites
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

May be present as a contaminate from fecal or vaginal material
Trichomonas vaginalis: parasite that causes trichomoniasis vaginitis
e. Spermatozoa
 May be present in men or women after intercourse
 Have round heads and long, slender, hairlike tails
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
3. Brand names
a. Uricult
b. Uricheck
4. Consists of slide attached to a screw cap
a. Each side of slide is coated with agar medium
 Suitable for growth of urinary bacteria
5. Do not use:
a. If agar is dehydrated
b. If mold or bacterial growth is present
6. Slide suspended in clean plastic vial: protects it from contaminants
7. Recommended urine specimen: clean-catch midstream
a. Collected after urine has been in bladder for 4 to 6 hours
b. Slide is dipped into the urine specimen
c. Slide is incubated
d. Slide is compared with a reference chart
Urine Pregnancy Testing
1. Purpose
a. To determine if a woman is pregnant
b. Before certain medications are given or procedures are performed
 That may cause injury to a fetus
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
Human Chorionic Gonadotropin
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
3. Highest level: occurs 8 weeks after conception
a. After this time: HCG declines
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4. 72 hours after delivery: HCG disappears entirely
5. Pregnancy tests more sensitive in first trimester
a. May even show a negative reaction during second and third trimester
6. Immunoassay tests
a. Used in medical office to detect pregnancy
b. Convenient to perform
c. Provide immediate test results
d. Positive and negative reactions
 Results in specific visible reaction
- That can be observed and interpreted
e. Commercially available in testing kits
 Contain required reagents and supplies
 Each kit performs a specific number of tests
 Product insert included
- Must follow exactly to prevent inaccurate test results
 Most are 99% accurate
- With low occurrence of false-positive test results
f. Brand names
 QuickVue One Step
 OSOM
 Clearview
g. Early prediction pregnancy tests
 May be able to detect pregnancy
- As early as 2–3 days before first missed period
(1) May sometimes show a false-negative result when performed
early
(a) Repeat later to confirm results
 Accurate results are more probable
- If urine is tested 1 week after a missed period
h. Takes approximately 5 minutes to perform
i. Results observed as a color change
j. Instructions for interpreting results
 Included in product insert
Guidelines for Urine Pregnancy Testing
1. Use clean, disposable urine containers
2. Preferred specimen: first-voided morning specimen
 Contains highest concentration of HCG
- However a random specimen can be used
3. Specific gravity should be determined before test
a. Less than 1.007: too dilute for testing
 Could cause a false-negative result
4. Urine specimen should be at room temperature
5. Kit should be stored according to information in the product insert
a. Most testing kits are stored at RT [between 59°F (15°C) and 86°F (30°C)]
 Away from direct sunlight
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6. Kit past expiration date: should not be used
7. If more than one patient is being tested
a. Label each testing device with patient’s name
 Prevents mixup of specimens
8. Most testing kits include an internal control
a. Performed at same time as testing procedure
b. Determines:
 Whether sufficient amount of specimen was added to cassette
 If correct technique was followed
c. If it does not perform as expected
 Test result is invalid
- Must retest the specimen
d. Document internal control in quality control log
 For first test run each day
9. Perform a positive and negative external control
a. With each new lot of urine pregnancy testing kits
• Monthly thereafter
b. External controls are used to:
• Determine if testing reagents are performing properly
• Detect any errors in technique
c. External controls:
 Consist of commercially available solutions
 May be included with test system
- Or may need to be purchased separately
d. Control procedure
 Performed in a similar manner
- To procedure for performing the test on a specimen collected from a
patient
 Instead of adding patient specimen to testing device
- Control is added
 Positive control: should produce a positive result
 Negative control: should produce a negative result
 Document result in a quality control log
e. Failure of external control to produce expected results may be due to:
• Deterioration of testing components due to improper storage
 Improper environmental testing conditions
 Errors in technique used to perform the procedure.
10. Conditions that can result in a positive result (other than normal pregnancy):
 Ectopic pregnancy
 Molar pregnancy
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
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3. Can detect pregnancy at approximately the eighth day after fertilization
a. 6 days before first missed period
4. Uses radioisotope technique
a. Capable of detecting minute amounts of HCG in the blood
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
Copyright © 2012, 2008, 2004, 2000, 1995, 1990, 1984, 1979 by Saunders, an imprint of Elsevier Inc.