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Urinalysis

Key Terms

anuria (ah-NOOR-ee-ah)

bilirubinuria (bill-ih-roo-bin-YUR-ee-ah)

bladder catheterization

diuresis (di-ah-REE-sis)

dysuria (dis-YUR-ee-ah)

frequency

glycosuria (glie-koe-SOO-ree-ah)

hematuria (hem-ah-TOOR-ee-ah)

ketonuria (kee-toe-NOO-ree-ah)

ketosis (kee-TOE-sis)

micturition (mik-tur-ISH-un)

nephron (NEF-ron)

nocturia (nok-TOOR-ee-ah)

nocturnal enuresis (nok-TOOR-nal en-YUR-ee-sas)

oliguria (oh-lig-YUR-ee-ah)

pH (PEE-AYCH)

polyuria (pol-ee-YUR-ee-ah)

proteinuria (proe-teen-YUR-ee-ah)

pyuria (pi-YUR-ee-ah)

renal threshold (REE-nul-THRESH-hold)

retention

specific gravity

supernatant (soo-per-NAY-tent)

suprapubic aspiration

urgency

urinalysis (yur-in-AL-ih-sis)

urinary incontinence

void (VOYD)

LEARNING OBJECTIVES	PROCEDURES
Urinary System
1. List conditions that may cause polyuria and oliguria. 2. Define the terms used to describe symptoms of the urinary system.
Collection of Urine
3. Explain why a first-voided morning specimen is often preferred for urinalysis. 4. Explain the purpose of collecting a clean-catch midstream specimen. 5. Explain the purpose of a 24-hour urine collection. 6. List changes that may occur if urine is allowed to remain standing for longer than 1 hour.	Instruct a patient in the procedure for collecting a clean-catch midstream urine specimen.
Analysis of Urine
7. List factors that may cause urine to have an unusual color or become cloudy. 8. Identify the various tests that are included in the physical and chemical examination of urine. 9. List the structures that may be found in a microscopic examination of urine.	Assess the color and appearance of a urine specimen.Perform a chemical assessment of a urine specimen.Prepare a urine specimen for microscopic analysis by the physician.
Urine Pregnancy Testing
10. Explain the basis for urine pregnancy tests. 11. List the guidelines that must be followed in a urine pregnancy test to ensure accurate test results.	Perform a urine pregnancy test.

Composition of Urine

A physiologic change in the body caused by disease can create a disturbance in one or more of the functions of the kidney. Detection of such a disturbance can be made with the examination of urine and other body fluids such as blood.

Urine is composed of 95% water and 5% organic and inorganic waste products. Organic waste products consist of urea, uric acid, ammonia, and creatinine. Urea is present in the greatest amounts and is derived from the breakdown of proteins. Inorganic waste products include chloride, sodium, potassium, calcium, magnesium, phosphate, and sulfate.

A normal adult excretes approximately 750 to 2000 mL of urine per day. This amount varies according to the amount of fluid consumed and the amount of fluid lost through other means, such as perspiration, feces, and water vapor from the lungs. An excessive increase in urine output is known as polyuria, with the urine volume exceeding 2000 mL in 24 hours. Polyuria may be caused by the excessive intake of fluids or the intake of fluids that contain caffeine (e.g., coffee, tea, cola), which is a mild diuretic. Certain drugs, such as diuretics, and the pathologic conditions of diabetes mellitus, diabetes insipidus, and renal disease also may result in polyuria. Decreased or scanty urine output is known as oliguria. In the case of oliguria, the urine volume is less than 400 mL in 24 hours. Oliguria may occur with decreased fluid intake, dehydration, profuse perspiration, vomiting, diarrhea, or kidney disease. The normal act of voiding urine is known as micturition.

Terms Related to the Urinary System

The medical assistant should have a thorough knowledge of the following terms used to describe symptoms associated with the urinary system:

Anuria Failure of the kidneys to produce urine

Diuresis Secretion and passage of large amounts of urine

Dysuria Difficult or painful urination

Frequency The condition of having to urinate often

Hematuria Blood present in the urine

Nocturia Excessive (voluntary) urination during the night

Nocturnal enuresis Inability of an individual to control urination at night during sleep (bedwetting)

Oliguria Decreased output of urine

Polyuria Increased output of urine

Pyuria Pus present in the urine

Retention The inability to empty the bladder. The urine is being produced normally but is not being voided

Urgency The immediate need to urinate

Urinary incontinence The inability to retain urine

Collection of Urine

The advantage of urine testing is that urine is readily available and obtaining it does not require an invasive procedure or the use of special equipment. For accurate test results, however, the medical assistant must adhere to proper urine collection procedures to obtain the proper specimen as ordered by the physician.

Guidelines for Urine Collection

The guidelines listed should be followed in collection of a urine specimen:

1. The medical assistant must obtain an adequate volume of urine as necessary for the type of test (usually 30 to 50 mL of urine).

2. Each specimen must be labeled properly with the patient’s name and date of birth, the date and time of collection, and the type of specimen (i.e., urine) to avoid any mix-ups in specimens.

3. Any medication the patient is taking should be recorded on the laboratory requisition and in the patient’s chart, because some medications may interfere with the accuracy of the test results.

4. If possible, the collection of a urine specimen should be avoided in women during menstruation and for several days thereafter because the specimen may become contaminated with blood. This results in a false-positive test result for blood in the urine.

5. The medical assistant should take into consideration that voiding may be difficult for patients under stress and anxiety. In these instances, understanding and patience should be conveyed to the patient.

6. A urine specimen may be difficult to obtain from a child, even with the assistance of a parent. In this case, the physician should be informed because another collection method may be used, such as a urine collection bag, suprapubic aspiration, or catheterization of the patient.

Urine Specimen Collection Methods

The type of test to be performed often dictates the method used to collect the urine specimen. A first-voided morning specimen is recommended for pregnancy testing, and a clean-catch midstream specimen is necessary for identification of the presence of a urinary tract infection (UTI).

Most offices use disposable plastic urine specimen containers. These containers are available in different sizes and come with lids to prevent spillage and to reduce bacterial and other types of contamination.

What Would You Do? What Would You Not Do?

Case Study 1

Yusuke Urameshi is at the office with fever and chills, frequency, and painful and difficult urination. The physician suspects that Mr. Urameshi has prostatitis and orders a clean-catch urine specimen for a complete urinalysis, including a microscopic examination of the sediment. Mr. Urameshi tries to collect the specimen but is able to collect only 5 mL of urine. He says that he is worried about what is wrong with him and he thinks his nervousness is making it hard to get a specimen. Mr. Urameshi says that it is probably just as well because he did not understand how to cleanse himself, and he is not sure that he did it right. 

Random Specimen

Urine testing in the medical office is often performed on freshly voided, random specimens. The medical assistant instructs the patient to void into a clean, dry, wide-mouthed container, and the urine is tested immediately at the medical office.

First-Voided Morning Specimen

In many cases, a first-voided morning specimen may be desired for testing because it contains the greatest concentration of dissolved substances, and a small amount of an abnormal substance that is present would be more easily detected. The patient should be instructed to collect the first specimen of the morning after rising and to preserve the specimen by refrigerating it until it is brought to the medical office. It is important to provide the patient with a specimen container to prevent the patient’s use of a container from home that might harbor contaminants and affect the test results.

Clean-Catch Midstream Specimen

The urinary bladder and most of the urethra are normally free of microorganisms, whereas the distal urethra and the urinary meatus normally harbor microorganisms. If the urine is being cultured and examined for bacteria, a clean-catch midstream specimen is necessary to prevent contamination of the specimen with these normally present microorganisms. Only microorganisms that may be causing the patient’s condition are desired in the urine specimen. A clean-catch midstream collection may be ordered for the detection of a UTI and the evaluation of the effectiveness of drug therapy in a patient undergoing treatment for such an infection.

The purpose of the clean-catch midstream collection is the removal of microorganisms from the urinary meatus and the distal urethra. This is accomplished by instructing the patient to thoroughly cleanse the area surrounding the meatus and to void a small amount of urine into the toilet, which flushes out microorganisms in the distal urethra. The urine specimen is collected in a sterile container using medically aseptic techniques. A properly collected specimen reduces the possibility of having to do a bladder catheterization or a suprapubic aspiration of the bladder. Bladder catheterization involves the passing of a sterile tube (the catheter) through the urethra and into the bladder to remove urine. Suprapubic aspiration involves the passing of a sterile needle through the abdominal wall into the bladder to remove urine. Both of these procedures must be performed using sterile technique.

Guidelines

Guidelines that should be followed when collecting a clean-catch midstream specimen are listed:

1. A clean-catch midstream specimen is collected by the patient at the medical office. The medical assistant must provide complete instructions for collection of this specimen. Failure to instruct the patient adequately may necessitate a return to the medical office for the collection of another specimen because of bacterial contamination. Patient instructions for obtaining a clean-catch midstream specimen are presented in Procedure 30-1.

 Procedure 30-1   Clean-Catch Midstream Specimen Collection Instructions 

Outcome

Instruct a patient in the procedure for collecting a clean-catch midstream urine specimen.

Equipment/Supplies

• Sterile specimen container and label

• Personal antiseptic towelettes

• Tissues

1. Procedural Step. Sanitize your hands. Greet the patient and introduce yourself. Identify the patient and explain the procedure.

2. Procedural Step. Assemble equipment. Label the specimen container with the patient’s name and date of birth, the date, the type of specimen (clean-catch midstream), and your initials.

3. Procedural Step. Instruct a female patient on collection of the specimen as follows:

a. Wash the hands, open the package of towelettes, and place them on their wrapper.

b. Remove the lid from the specimen container and place it on a paper towel with the opening of the lid facing upward. Do not touch the inside of the lid or the inside of the specimen container.

c. Pull undergarments down and sit on the toilet. Expose the urinary meatus by spreading apart the labia with one hand.

d. Cleanse each side of the urinary meatus with an antiseptic towelette using a front-to-back motion (from pubis to anus). Use a separate antiseptic towelette for each side of the meatus. After use, discard each towelette in the toilet.

    Principle. Cleansing removes microorganisms from the urinary meatus. A front-to-back motion must be used for cleansing to avoid drawing microorganisms from the anal region into the area that is being cleansed.

e. Cleanse directly across the meatus (front to back) with a third antiseptic towelette.

f. Continue to hold the labia apart, and void a small amount of urine into the toilet.

    Principle. Voiding a small amount flushes microorganisms out of the distal urethra.

g. Without stopping the urine flow, collect the next amount of urine by voiding into the sterile container. Do not touch the inside of the container. Fill the specimen container about half full with urine.

    Principle. Touching the inside of the container contaminates it with microorganisms that normally reside on the skin.

h. Void the last amount of urine into the toilet. This means that the first and last portions of the urine flow are not included in the specimen. Replace the lid of the specimen container.

i. Wipe the area dry with a tissue, and discard it in the toilet. Flush the toilet and wash the hands.

4. Procedural Step. Instruct a male patient as follows:

a. Wash the hands, open the towelettes, remove the lid from the specimen container, and remove undergarments.

b. Stand in front of the toilet. Retract the foreskin of the penis (if uncircumcised).

c. Cleanse the area around the meatus (glans penis) and the urethral opening (meatal orifice) by wiping each side of the meatus with a separate antiseptic towelette.

d. Cleanse directly across the meatus with a third antiseptic towelette. After use, discard each towelette in the toilet.

e. Void a small amount of urine into the toilet.

f. Collect the next amount of urine by voiding into the sterile container without touching the inside of the container with the hands or penis. Fill the container about half full with urine.

g. Void the last amount of urine into the toilet and replace the lid on the container.

h. Wipe the area dry with a tissue, and discard it in the toilet. Flush the toilet and wash the hands.

5. Procedural Step. Provide the patient with instructions about what to do with the specimen after it has been collected (e.g., placing it in a designated area, directly handing it to the medical assistant).

6. Procedural Step. Record the procedure in the patient’s chart. Include the date and time and the type of specimen collected (clean-catch midstream collection).

7. Procedural Step. Test the specimen at the office or prepare the specimen for transport to an outside laboratory for testing. If the specimen is to be transported to an outside laboratory, do the following:

a. Place the specimen container in a biohazard specimen bag.

b. Place the laboratory request in the outside pocket of the specimen bag.

c. Properly preserve the specimen while awaiting pickup by a laboratory courier by placing it in a refrigerator.

d. Chart the date the specimen was transported to the laboratory and the tests requested.

2. The medical assistant must label the container with the patient’s name and date of birth, the date, the time of collection, and the type of specimen (clean-catch midstream specimen).

3. For reliable test results, the specimen should be tested immediately and should not be allowed to stand. If this is not possible, the specimen should be refrigerated, or a preservative should be added.

4. If the specimen is to be tested at an outside laboratory, completion of a laboratory requisition to accompany it is necessary. A urinalysis laboratory request form is shown in Figure 30-1.

5. The procedure is completed by sanitizing the hands and recording the procedure in the patient’s chart. The information to be charted for specimens tested at the medical office includes the date and time, the type of specimen collected, and the laboratory test results. If the specimen is being transported to an outside laboratory for testing, record the date and time, the type of specimen collected, and the date the specimen was transported to the laboratory.

Twenty-Four–Hour Urine Specimen

A 24-hour urine specimen is used for quantitative measurement of specific urinary components. With collection of urine over a 24-hour period, greater accuracy of measurement exists than with a random specimen. This is because body metabolism, exercise, and hydration can affect the excretion rate of substances in the urine. In addition, at certain times during a 24-hour period, increased excretion of substances (e.g., electrolytes, hormones, proteins, urobilinogen) is seen, and at other times decreased excretion is seen. Examples of substances measured in a 24-hour specimen include calcium, cortisol, lead, potassium, protein, and urea nitrogen. A 24-hour specimen is often used in the diagnosis of the cause of kidney stone formation and in the control and prevention of new stone formation. It may also be used to perform a creatinine clearance test, which provides the physician with information on kidney function.

A large wide-mouthed container (3000 mL) is used to store the urine collected over the 24-hour period. To prevent changes in the quality of the urine specimen, the specimen must be kept refrigerated or placed in an ice chest. Some containers also contain a chemical preservative (in the form of crystals, tablets, or a liquid) to assist in maintaining the quality of the specimen. Examples of urine preservatives include hydrochloric acid, boric acid, acetic acid, and toluene. A hazardous chemical warning label should be attached to a specimen container with a preservative, and the patient should be instructed not to discard or touch the preservative in the container.

The patient is also provided with a container in which to collect each urine specimen. A female patient may be given a urine “hat,” which is placed over the commode under the toilet seat; a male patient is often provided with a collection cup. After collection, the urine is poured into the large specimen container. This method makes collection easier and safer for the patient. If the patient voids urine directly into a specimen container that holds a preservative, the preservative could splash onto the patient’s skin, resulting in a chemical burn.

The medical assistant should provide the patient with verbal and written instructions for collection of the urine specimen. The patient should be advised to drink a normal amount of fluid during the collection period and to avoid alcohol intake for 24 hours before and during the collection period. The patient should be instructed to choose a 24-hour period when he or she will be at home, so that the urine will not have to be transported. The test should not be performed when the patient is menstruating. Certain medications, such as thiazides, phosphorus-binding antacids, allopurinol, and vitamin C, could alter the test results. The physician may want the patient to discontinue these medications for 1 week before the test.

Analysis of Urine

Urinalysis is the analysis of urine and is the laboratory test most commonly performed in the medical office because a urine specimen is readily obtainable and can be easily tested. Urinalysis consists of physical, chemical, and microscopic examinations. Deviation from normal in any of the three areas assists the physician in the diagnosis and treatment of pathologic conditions, not only of the urinary system, but also of other body systems. Urinalysis may be performed as a screening measure as part of a general physical examination or to assist in the diagnosis of a pathologic condition. It also may assist in the evaluation of effectiveness of therapy after treatment has been initiated for a pathologic condition.

Urinalysis should be performed on a fresh or preserved specimen. If a specimen cannot be examined within 1 hour of voiding, it should be preserved at once in the refrigerator in a closed container and later returned to room temperature and mixed before testing. Chemical additives also are used to preserve urine specimens but generally are used only with specimens that require prolonged storage, such as specimens that must be shipped a long distance, because the chemical preservative sometimes interferes with the chemicals used to perform the urine test.

If the urine is allowed to stand at room temperature for longer than 1 hour, some of the following changes may occur:

1. Bacteria in the environment that get into the urine specimen work on the urea present in the urine, converting it to ammonia. Because ammonia is alkaline, an acid urine becomes alkaline, increasing the pH. In addition, an alkaline pH may result in a false-positive result on the protein test.

2. Bacteria multiply rapidly in the urine, resulting in a cloudy specimen and an increase in the nitrite.

3. If glucose is present in the specimen, it decreases in amount because microorganisms use the glucose as a source of food.

4. If any red or white blood cells are present, they may break down.

5. Casts decompose after several hours.

Physical Examination of Urine

The physical examination of urine includes determination of the color, appearance, and specific gravity. The color and appearance of the urine specimen may be evaluated during preparation for another testing procedure, such as chemical testing of the urine, or before centrifugation of the specimen in preparation for microscopic analysis. For an accurate evaluation of the color and appearance, the urine specimen must be collected in a clear plastic container.

Color

The normal color of urine ranges from almost colorless to dark yellow. Dilute urine tends to be lighter yellow in color, whereas concentrated urine is a darker yellow. The first-voided morning specimen is usually the most concentrated because consumption of fluids is decreased during the night. Urine becomes more dilute as the day progresses and more fluids are consumed.

The color of the urine is the result of the presence of a yellow pigment known as urochrome, produced by the breakdown of hemoglobin. It is common for the color of urine to vary among different shades of yellow within the course of a day. Classifications that can be used to describe the color of urine include light yellow, yellow, dark yellow, light amber, amber, and dark amber (Figure 30-2).

The color of the urine specimen assists in determining additional tests that may be necessary. Abnormal colors may be caused by the presence of hemoglobin or blood (resulting in a red or reddish color), bile pigments (resulting in a yellow-brown or greenish color), and fat droplets or pus (resulting in a milky color). Some foods and medications also may cause the urine to change to an abnormal color. Phenazopyridine (Pyridium), a urinary tract analgesic, causes the urine to change to an orange to red color.

Appearance

Evaluation of the appearance of urine is usually performed at the same time as the color evaluation. Fresh urine is usually clear, or transparent, but becomes cloudy on standing out too long. Cloudiness in a freshly voided specimen may be the result of the presence of bacteria, pus, blood, fat, yeast, sperm, mucous threads, or fecal contaminants. A microscopic examination of the urine sediment should be performed on all cloudy specimens to determine the cause of the cloudiness. Cloudiness resulting from bacteria may be caused by a UTI.

Classifications used to describe the appearance of urine include clear, slightly cloudy, cloudy, and very cloudy (Figure 30-3). The medical assistant should develop skill in recognizing the varying degrees of urine clarity.

Odor

Freshly voided urine normally should have a slightly aromatic odor. Urine that has been standing for a long time develops an ammonia odor from the breakdown of urea by bacteria in the specimen. The urine of a patient with diabetes mellitus may have a fruity odor from the presence of ketone. The urine of a patient with a UTI is usually foul-smelling, and the odor becomes worse on standing. Certain foods, such as asparagus, can cause the urine to have a musty smell. Although urine may have many characteristic odors, as a rule the odor of urine is not generally used in the diagnosis of a patient’s condition.

Specific Gravity

The specific gravity of urine measures the weight of the urine compared with the weight of an equal volume of distilled water. Specific gravity indicates the amount of dissolved substance present in the urine, providing information on the ability of the kidneys to dilute or concentrate the urine. Specific gravity is decreased in conditions in which the kidneys cannot concentrate the urine, such as chronic renal insufficiency, diabetes insipidus, and malignant hypertension. The specific gravity is increased in patients with adrenal insufficiency, congestive heart failure, hepatic disease, diabetes mellitus with glycosuria, and conditions that cause dehydration, such as fever, vomiting, and diarrhea.

The normal specific gravity of urine ranges from 1.003 to 1.030 but is usually between 1.010 and 1.025 (the specific gravity of distilled water is 1.000). Specific gravity varies greatly with fluid intake and the state of hydration of an individual. Dilute urine contains fewer dissolved substances and has a lower specific gravity. Concentrated urine has a higher specific gravity because of the increased amount of dissolved substances. A urine specimen is generally more concentrated in the morning and becomes more dilute after fluid consumption.

In the medical office, specific gravity is most commonly measured using a reagent strip. This involves a color comparison determination with a reagent strip that contains a reagent area for specific gravity. The reagent strip is dipped into the urine specimen, and the results are compared with a color chart (see Procedure 30-2).

 Procedure 30-2   Chemical Testing of Urine with the Multistix 10 SG Reagent Strip 

Outcome

Perform a chemical assessment of a urine specimen.

Equipment/Supplies

• Disposable gloves

• Multistix 10 SG reagent strips

• Urine container

• Timer

• Laboratory report form

1. Procedural Step. Perform the quality control testing procedure if using a new bottle of testing strips.

    Principle. Performing the quality control procedure ensures the reliability of test results.

2. Procedural Step. Obtain a freshly voided urine specimen from the patient with a clean container. The specimen should be uncentrifuged and at room temperature.

    Principle. The best results are obtained with a freshly voided specimen. The container should be clean because contaminants could affect the results. Uncentrifuged specimens ensure a homogeneous sample.

3. Procedural Step. Sanitize your hands.

4. Procedural Step. Assemble the equipment. Check the expiration date of the reagent strips.

    Principle. Outdated reagent strips may lead to inaccurate test results.

5. Procedural Step. Apply gloves. Remove a reagent strip from its plastic container, and recap the container immediately. Do not touch the test areas with your fingers or lay the strip on the table. It is permissible, however, to lay the reagent strip on a clean, dry paper towel.

    Principle. Recapping the container is necessary to prevent exposing the strips to environmental moisture, light, and heat, which cause altered reagent reactivity. Contamination of test areas by the hands or table surface may affect the accuracy of test results.

6. Procedural Step. Thoroughly mix the urine specimen and remove the lid from the container. Using the dominant hand, completely immerse the reagent strip in the urine specimen, and remove it immediately. While removing, run the edge of the strip against the rim of the urine container to remove excess urine.

    Principle. The strip should be completely immersed to ensure that all test areas are moistened for accurate test results. Prolonged immersion of the reagent strip and failure to remove excess urine may cause the reagents to dissolve and leach onto adjacent test areas, affecting the accuracy of the test results.

7. Procedural Step. With the nondominant hand, start the timer, pick up the reagent strip container, and rotate it to the color chart. Hold the reagent strip in a horizontal position and place it as close as possible to the corresponding color blocks on the color chart. Do not lay the strip directly on the color chart because this will result in soiling of the chart by the urine. Read the results carefully and at the exact reading times, starting with the shortest time specified on the color chart and as indicated here:

Glucose, 30 seconds	Bilirubin, 30 seconds
Ketone, 40 seconds	Specific gravity, 45 seconds
Blood, 60 seconds	pH, 60 seconds
Protein, 60 seconds	Urobilinogen, 60 seconds
Nitrite, 60 seconds	Leukocytes, 2 minutes

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