Chapter 42 Urinalysis

Urine Formation Urine forms in kidneys and leaves body through urinary tract system The urinary system >> [FIGURE 42-1]

Urine Formation Kidney regulates fluid outside cells of body Maintains homeostasis Two kidneys, one on each side of body; 11 to 12 cm long and 5 to 6 cm wide Please see the Animations/Videos button to view the clip.

Urine Formation Filtration Glomerulus filters waste products, salts, excess fluid from blood Tubule concentrates filtered material Nephron Combination of glomerulus and tubule One million nephrons in each kidney

Urine Formation Filtration Substances filtered out from body Water Ammonia Electrolytes Glucose Amino acids Creatinine Urea

Urine Formation Reabsorption About 180 liters of filtrate produced daily Only 1–2 liters of urine eliminated Much filtrate reabsorbed into body Blood cells and most proteins stay in blood Concentration of glucose in blood below 180 mg/dl will be reabsorbed Glucose is threshold substance

Urine Formation Secretion Substances not already filtered secreted into urine through distal convoluted tubule Hydrogen and ammonium ions may be secreted into urine in exchange of sodium

Urine Composition After passing through kidney, urine 96% water and 4% dissolved substances (urea, salt, sulfates, phosphates) (See Table 42-1: Normal and Abnormal Substances in Urine)

Urine Composition Abnormal constituents of urine Red and white blood cells Fat Glucose Casts Bile Acetone Hemoglobin

Urine Composition Changes in urine production Amount of urine excreted can increase or decrease Urine color can change Urine appearance can vary

Urine Composition Changes in urine production Urine odor can change Cells can be present in urine Chemical constituents in urine can change Urine concentration (specific gravity) may vary

Safety Standard Precautions Transmission-Based Precautions Biohazard precautions

Quality Control Regulatory agencies Quality control (QC) programs Written testing protocols Maintained testing records Recalibration of instruments

Quality Control Documentation of daily control testing must be kept at least 3 years Commercially available urine control samples Run positive and negative controls each day on all tests

CLIA ’88 Appropriate training in methodology of test being performed Understanding of urine testing QC procedures Proficiency in use of instrumentation; being able to troubleshoot problems

CLIA ’88 Knowledge of stability and proper storage of reagents Awareness of factors that influence test results Knowledge of how to verify test results CLIA categorizes microscopic exam of urine as a PPMP

Urine Containers Types Nonsterile containers for random specimens Sterile containers for cultures 24-hour collection containers with added preservatives [FIGURE 42-3]

Urine Containers Before handing urine specimen cup to patient, label with patient’s name, date, time Follow protocol of your facility Use permanent marker Always label cup, not lid

Urine Collection Urine specimen types Random (spot) specimen Obtained at any time Most common Patient should be able to provide specimen within 15 to 20 minutes of drinking several cups of water

Urine Collection Urine specimen types First morning void specimen Most concentrated specimen Higher acid pH Preferred, but seldom ordered

Urine Collection Urine specimen types Fasting/timed specimens Provider wants to measure substance without interference from food intake Length of fast varies Give patient written directions Use regular urinalysis container

Urine Collection Urine specimen types 24-hour specimen Circadian rhythm and intake of food and water determine concentration of substances during 24-hour period Requested when quantitative tests for different substances desired Expressed in units per 24 hours Use of preservatives and refrigeration Sometimes use 2-hour or 12-hour collection instead

Urine Collection Collection methods Clean-catch midstream Cleanse genital area before collection Patient should begin to urinate into toilet Pulls cup into urine stream and collects sample Removes cup from stream and voids rest of urine into toilet

Urine Collection Collection methods Catheterized Insertion of sterile tube into bladder through urethra Completely sterile specimen Only performed under provider’s order and only by health care professionals who have been trained Can cause infection if not done correctly

Urine Collection Collection methods Culture and sensitivity of urine MA responsible for preparing sample for transport Urine Culture and Sensitivity Transport kit (See Procedure 42-6: Utilizing a Urine Transport System for C&S)

Examination of Urine Fresh state, preferably still warm Urinalysis performed as soon as possible, preferably within 2 hours

Examination of Urine Physical examination of urine Assess volume of urine specimen, making sure amount sufficient for testing Note any unusual urine odor Measure specific gravity of specimen (See Procedure 42-1: Assessing Urine Volume, Color, and Clarity (Physical Urinalysis)) (See Procedure 42-2: Using the Refractometer to Measure Specific Gravity (Physical Urinalysis Continued))

Examination of Urine Physical examination of urine [FIGURE 42-4] Physical examination of urine Observe and record color, appearance, transparency

Examination of Urine Physical examination of urine Specimen volume First step in performing urinalysis Enough urine to fill test tube with 10 mL of urine Urine color Ranging from pale yellow to dark yellow or amber Result of concentration of urine Diet and certain drugs can add color (See Table 42-2: Urine Colors and Possible Causes)

Examination of Urine Physical examination of urine Urine transparency Clear, cloudy, hazy, turbid (opaque) Urine odor Odors should not be disregarded Sweet (diabetic ketoacidosis) Foul (bacteria)

Examination of Urine Physical examination of urine Urine specific gravity Ratio of weight of given volume of substance to weight of same volume of distilled water at same temperature Concentrations of solids in urine Tested by using test strip, urinometer, refractometer

Examination of Urine Physical examination of urine Urinometer Measures specific gravity Calibrated, floating device Least accurate method and most difficult

Examination of Urine Refractometer Most common tool for determining specific gravity of liquids Measures refractive index of urine Reads about 0.002 less than that of true specific gravity Needs 1 drop of urine Easy to use and reliable [FIGURE 42-5A]

Examination of Urine Physical examination of urine Reagent test strips Available through medical laboratory supply companies Look for SG in name More tests on reagent test strips, more expensive the product

Examination of Urine Chemical examination of urine Use of reagent strips with color-coded chart Chemical testing available on urine reagent test strips [FIGURE 42-16C]

Examination of Urine Chemical examination of urine Specific reagent test strips Glucose pH Protein Ketones Bilirubin

Examination of Urine Chemical examination of urine Specific reagent test strips Blood Urobilinogen Nitrite Leukocytes Specific gravity (See Table 42-3: Chemical Testing Available on Urine Reagent Test Strips)

Examination of Urine Chemical examination of urine Reagent test strip quality control Automated urine analyzers >> [FIGURE 42-7E] (See Procedure 42-5: Performing a Complete Urinalysis) (See Table 42-4: Reagent Strip Sensitivity)

Examination of Urine Microscopic examination of urine sediment Considered as PPMP Sediment at bottom of centrifuge tube Helps determine kidney disease, disorders of urinary tract, systemic disease Freshly voided urine Use of urine color atlas Use of urine stains

Examination of Urine Microscopic examination of urine sediment Sediment components Centrifuge 10–15 mL of urine Pour off supernatant urine Resuspend sediment by tapping Put drop of sediment on slide

Examination of Urine Sedi-Stain® example of stain used in laboratories >> [FIGURE 42-8]

Abnormal Urine Sediment Cells and Microorganisms RBC WBC Renal tubular epithelial cells Bacteria Yeast Parasites Sperm Artifacts Squamous epithelial cells

Examination of Urine Crystals in urine sediment Insignificant part of urinary sediment Calcium phosphate, triple phosphate, calcium oxalate, amorphous phosphates and urates, calcium carbonate Form as urine specimens stand May indicate disease: uric acid, cystine, sulfa drug crystals

Examination of Urine Casts in urine sediment Important to see and identify Formed when protein accumulates and precipitates in kidney tubules Appearance of casts Hyaline cast most common kind seen Granular casts and cellular casts also seen Takes experienced eye to identify (See Procedure 42-4: Preparing Slide for Microscopic Examination of Urine Sediment) (See Procedure 42-5: Performing a Complete Urinalysis)

Urinalysis Report Include patient’s name, type of specimen, collection method, ordering provider, MA name, date and time of collection, date and time of testing, findings [FIGURE 42-13]

Drug Screening Becoming more common for employment Test itself is CLIA waived, but detailed protocols must be followed Chain of custody