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CHAPTER 16. URINALYSIS. PRETEST. True or False. The urinary system functions to regulate the fluid balance of the body. The functional unit of the kidney is the nephron. An excessive increase in urine output is termed polyuria.
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CHAPTER 16 URINALYSIS
PRETEST True or False • The urinary system functions to regulate the fluid balance of the body. • The functional unit of the kidney is the nephron. • An excessive increase in urine output is termed polyuria. • A clean-catch midstream urine specimen is required for a urine culture. • Urinalysis consists of a physical, chemical, and microscopic examination of urine.
PRETEST, CONT. True or False • A urine specimen that is light yellow in color indicates that bacteria are present in the specimen. • The pH of most urine specimens is neutral. • Blood may normally be present in the urine due to menstruation. • Hematuria refers to the presence of blood in the urine. • HCG is a hormone that is present in the urine and blood of a pregnant woman.
Content Outline Function of urinary system Regulate fluid and electrolyte balance of the body Remove wastes Structure and Function of the Urinary System
Structure and Function of the Urinary System, cont. Kidneys Bean-shaped organs: 4½ inches long and 2 to 3 inches wide Located in lumbar region Produces urine
Structure and Function of the Urinary System, cont. • Ureters • 10 to 12 inches in length and ½ inch in diameter • Propels urine into urinary bladder • By force of gravity and the peristaltic waves of the ureters
Structure and Function of the Urinary System, cont. • Urinary bladder • Hollow, muscular sac • Holds approximately 500 ml of urine • Stores and expels urine
Structure and Function of the Urinary System, cont. • Urethra • Tube that extends from bladder to outside • Urinary meatus: external opening of urethra • Males: urethra transports urine and reproductive secretions • Females: urethra transports urine only
Urinary System Modified from Applegate EJ: The anatomy and physiology learning system, ed 2, Philadelphia, 2000, Saunders.
Nephron • Nephron • Each kidney composed of approximately 1 million smaller units known as nephrons • Nephron: Functional unit of the kidney
Nephron, cont. • Function: Filters wastes from blood and dilutes them with water to produce urine • Reabsorbs substances needed by the body: • Water • Glucose • Electrolytes
Nephron From Applegate EJ: The anatomy and physiology learning system, ed 2, Philadelphia, 2000, Saunders.
Composition of Urine • Physiologic change in body caused by disease: • Can create a disturbance in kidney function • Can be detected by examination of urine
Composition of Urine, cont. • Urine composed of: • Water: 95% • Organic and inorganic waste products: 5% • Organic wastes: urea, uric acid, ammonia, and creatinine • Urea present in greatest amounts • Derived from breakdown of proteins • Inorganic wastes: chloride, sodium, potassium, calcium, magnesium, phosphate, sulfate
Composition of Urine, cont. • Normal adult: excretes 750 to 2000 ml of urine per day • Varies based on: • Amount of fluid consumed • Amount lost through other means (perspiration, feces)
Composition of Urine, cont. • Polyuria: excessive increase in urine output • Caused by: • Excessive intake of fluids • Intake of fluids that contain caffeine (mild diuretic) • Drugs (diuretics) • Pathological conditions (e.g., diabetes, renal disease)
Composition of Urine, cont. • Oliguria: decreased output of urine • Caused by: • Decreased fluid intake· • Dehydration • Profuse perspiration • Vomiting • Diarrhea • Kidney disease
Terms Relating to 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 urine
Terms Relating to the Urinary System, cont. • Nocturia: excessive (voluntary) urination during the night • Nocturnal enuresis: the inability of the patient to control urination at night during sleep (bedwetting) • Pyuria: pus present in the urine
Terms Relating to the Urinary System, cont. • 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 • Advantages of urine testing • Urine is easily available • Does NOT require: • An invasive procedure • Use of special equipment
Collection of Urine, cont. • To obtain accurate urine test results: • Adhere to proper urine collection procedures • Ensures collection of proper specimen
Guidelines for Urine Collection • Make sure to obtain an adequate volume (usually 30 to 50 ml) • Properly label each specimen: avoids mix-up of specimens • Patient's name • Date and time of collection • Type of specimen
Guidelines for Urine Collection, cont. • Record medications patient is taking on laboratory requisition and in patient's chart: • Some medications interfere with accuracy of test results • Do not collect specimen during menstruation: • May contaminate specimen with blood • Result in false-positive results on test for blood
Guidelines for Urine Collection, cont. • Difficult for some patients to void under stress and anxiety • Be patient and relay understanding to patient
Guidelines for Urine Collection, cont. • May be difficult to obtain from a child: • May need to use another collection method: • Urine collection bag • Suprapubic aspiration • Catheterization
Urine Specimen Collection Methods • Type of test being performed: often dictates the collection method • Examples: • Pregnancy test: first-voided morning specimen • Identification of a urinary tract infection (UTI): clean-catch midstream collection
Urine Specimen Collection Methods, cont. • Most offices use disposable plastic specimen containers • Available in different sizes • Have lids to: • Prevent spillage • Reduce contamination of the specimen
Random Specimen • Random Specimen • Urine testing often performed on a freshly voided specimen • MA instructs patient to void into clean, dry, wide-mouthed container • Urine tested immediately
First-Voided Morning Specimen • First-Voided Morning Specimen • Contains greatest concentration of dissolved substances • Small amount of a substance detected more easily • Instruct patient to collect first specimen of the morning • Preserve in refrigerator
First-Voided Morning Specimen, cont. • Provide patient with specimen container • To prevent use of a container that harbors contaminants • Could cause inaccurate test results
Clean-Catch Midstream Specimen • Clean-Catch Midstream Specimen • 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.
Clean-Catch Midstream Specimen, cont. • Microorganisms are normally present in: • Distal urethra • Urinary meatus Modified from Applegate EJ: The anatomy and physiology learning system, ed 2, Philadelphia, 2000 Saunders.
Clean-Catch Midstream Specimen, cont. • Clean-catch: required when urine is cultured and examined for bacteria • Only microorganisms causing patient's condition are desired in specimen • Ordered for: • Detection of a UTI • Evaluate effectiveness of drug therapy for a UTI
Clean-Catch Midstream Specimen, cont. • 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
Clean-Catch Midstream Specimen, cont. • 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
Clean-Catch Midstream Specimen, cont. • Guidelines • Collected by patient at office • MA provides instructions: • Provide complete instructions: • To prevent contamination of specimen with bacteria • Avoid patient having to collect another specimen
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)
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
The 24-Hour Urine Specimen • Quantitative measurement of specific urinary components • Greater accuracy of measurement than with random specimen
The 24-Hour Urine Specimen, cont. • Examples of substances measured: • Calcium • Creatinine • Lead • Potassium • Protein • Urea nitrogen
The 24-Hour Urine Specimen, cont. • Often used to: • Diagnose the cause of kidney stone formation • Assist in control and prevention of new stone formation
The 24-Hour Urine Specimen, cont. • Large container used (3000 ml) • Specimen must be kept refrigerated • To prevent changes in the quality of the specimen • Some containers also contain a preservative
The 24-Hour Urine Specimen, cont. • MA should provide both written and verbal instructions • Moderately limit fluid intake • Avoid alcohol for 24 hours before and during collection • Physician may want patient to discontinue certain medications for 1 week before test
Analysis of Urine • Urinalysis:analysis of urine • Consists of: • Physical examination • Chemical examination • Microscopic examination
Analysis of Urine, cont. • Deviation from normal on urinalysis • Assists in diagnosis and treatment of pathologic conditions of: • Urinary system • Other body systems
Analysis of Urine, cont. • May be performed: • As screening measure • Part of physical examination • Assist in diagnosis of a patient's condition • Evaluate effectiveness of therapy