AUBF Lab Module 1: Urine Analysis PDF

ANALYSIS OF URINE AND BODY FLUIDS LABORATORY A.Y 2024-2025 MODULE 1 – INTRODUCTION TO URINALYSIS (URINE SPECIMEN) INTRODUCTION...

ANALYSIS OF URINE AND BODY FLUIDS LABORATORY A.Y 2024-2025 MODULE 1 – INTRODUCTION TO URINALYSIS (URINE SPECIMEN) INTRODUCTION o Additionally, tubes with conical bottoms for sediment analysis or round bottoms for automated reagent strip OVERVIEW testing. Specific information on specimen collection and handling should be stated at the beginning of each procedure listed in the LABELS manual. All specimens must be labeled immediately after collection with Requisition forms and computerized entry forms should the: designate the type of urine specimen to be collected and the o Patient’s last and first name with identification number date and time of collection. (inpatients) The form should include space for recording: o Date and time of collection o The actual date and time of specimen collection o Method of collection o Whether the specimen was refrigerated before transporting o Type of specimen o The time the specimen was received in the laboratory and o Interfering medicines the time the test was performed o Time of receiving the specimen o Tests requested o Additional information such as: o An area for specific instructions that might affect the results ▪ Patient’s age and location of the analysis ▪ Healthcare provider’s name o Patient identification information ▪ Preservatives used ▪ Patient’s sex Labels must be attached to the body of the container, not to the ▪ Age or date of birth lid, and should not become detached if the container is ▪ When appropriate, the source of the specimen refrigerated or frozen. ▪ The time it was collected must be documented REQUISITION FORM LESSON 1: URINE SPECIMEN Requisition form – can either be manual or computerized; must accompany specimens delivered to the laboratory. SPECIMEN COLLECTION o The information on the form must match the information on Urine – it is a biohazardous substance whose handling requires the specimen label. the observance of Standard Precautions (SP). Additional information on the form can include: o Gloves should be worn at all times when in contact with the o Method of collection urine specimen. o Type of specimen The type of urine collection container, as well as specimen o Possible interfering medications preservation and storage, will affect the quality of the urine test o Patient’s clinical information results. The time the specimen is received in the laboratory should be Written criteria for the collection, preservation, handling, storage, recorded on the form. and labeling of urine must be available. SPECIMEN REJECTION CONTAINERS The laboratory should reject specimens that are improperly Specimens must be collected in a clean, dry, leakproof labeled and/or collected, and appropriate personnel should be containers. notified to collect a new specimen. Disposable containers – should be used because they eliminate Situations leading to specimens that should be rejected can the chance of contamination due to improper washing. include: These disposable containers are available in a variety of sizes 1. Specimens in containers that are unlabeled or improperly and shapes, including bags with adhesive for the collection of labeled. pediatric specimens and large containers for 24-hour 2. Labels and requisition forms that do not match. specimens. 3. Specimens contaminated with feces or toilet paper. o Properly applied screw-top lids are less likely to leak than 4. Containers with contaminated exteriors. are snap-on lids. 5. Specimens of insufficient quantity (volume). Containers for routine urinalysis should have a wide mouth to 6. Specimens that have been transported improperly. facilitate collections from female patients and a wide, flat bottom to prevent overturning. SPECIMEN HANDLING They should be made of a clear material to allow for The fact that a urine specimen is so readily available and easily determination of color and clarity. collected often leads to laxity in the treatment of the specimen The recommended capacity of the container is 50 mL, which after its collection. allows 12 mL of specimen needed for microscopic analysis, Changes in urine composition take place not only in vivo (within additional specimen for repeat analysis, and enough room for the living) but also in vitro (in glass), requiring correct handling the specimen to be mixed by swirling the container. procedures. Individually packaged sterile containers with secure closures should be used for microbiological studies of urine. SPECIMEN INTEGRITY o Sterile containers are also suggested if more than 2 hours After collection, specimens should be delivered to the laboratory elapse between specimen collection and analysis. promptly and tested within 2 hours. BD Vacutainer Urine Transfer Straw – is a nonsterile, plastic A specimen that cannot be delivered and tested within 2 hours holder device that contains a needle with a straw attachment should be refrigerated or have an appropriate chemical that can be used with the collection container to fill evacuation preservative added. tubes. Most significant changes may occur in a specimen allowed to o This device allows for the sterile transfer of urine to tubes remain unpreserved at room temperature for longer than 2 containing preservatives for microbiology testing. hours. o These changes are related to the growth of bacteria. [AUBF Laboratory: Module 1 Discussion] CHANGES IN UNPRESERVED URINE (LONG-STANDING SAMPLE) Analyte Change Cause Color Modified/darkened - Oxidation or reduction of metabolites Clarity Decreased - Bacterial growth and precipitation of amorphous material Odor Increased ammonia smell - Bacterial multiplication causing breakdown of urea to ammonia pH Increased - Breakdown of urea to ammonia by urease-producing bacteria/loss of CO2 Glucose Decreased - Glycolysis and bacterial use Ketones Decreased - Volatilization and bacterial metabolism Bilirubin Decreased - Exposure to light/photo oxidation to biliverdin Urobilinogen Decreased - Oxidation to urobilin Nitrite Increased - Multiplication of nitrate-reducing bacteria RBC and WBC casts Decreased - Disintegration/lyse in dilute alkaline urine Bacteria Increased - Multiplication Trichomonas Decreased - Loss of motility, death SPECIMEN PRESERVATION (URINE) 5. COMMERCIAL PRESERVATIVE TABLETS The method of preservation used most routinely is refrigeration Advantage: Convenient when refrigeration not possible; have at 2°C to 8°C, which decreases bacterial growth and metabolism. controlled concentration to minimize interference. If the urine is to be cultured, it should be refrigerated during Disadvantage: Check tablet composition to determine possible transit and kept refrigerated until cultured, up to 24 hours. effects on desired tests. The specimen must return to room temperature before chemical testing by reagent strips. 6. URINE COLLECTION KITS Refrigeration also can cause precipitation of amorphous urate Advantage: Contains collection cup, transfer straw, culture and and phosphate crystals. sensitivity (C&S) preservative tube, or UA tube. When a specimen must be transported over a long distance and refrigeration is impossible, chemical preservatives may be 7. LIGHT AND GRAY C&S TUBE added. Advantage: Specimen stable at room temperature (RT) for 48 Commercially prepared transport tubes with a lyophilized hours; prevents bacterial growth and metabolism. preservative are available that allow for the transport, testing, Disadvantage: Do not use if urine is below minimum fill line. and storage of the urine specimens. Preservative is boric acid, sodium borate, and sodium formate. The ideal preservative should be: Keeps pH at about 6.0. o Bactericidal, o Inhibit urease 8. YELLOW PLUS UA TIUBE o Preserve formed elements in the sediment Advantage: Use on automated instruments. o Should not interfere chemical test Disadvantage: Must refrigerate within 2 hours. Round or conical bottom, no preservative. URINE PRESERVATIVES 9. CHERRY RED/YELLOW PRESERVATIVE PLUS TUBE 1. REFRIGERATION Advantage: Specimen stable for 72 hours at RT; instrument- Advantage: Does not interfere with chemical tests. compatible. Disadvantage: Precipitates amorphous phosphates and urates. Disadvantage: Must be filled to minimum fill line; bilirubin and Prevents bacterial growth for 24 hours. urobilinogen may be decreased if specimen is exposed to light and left at RT. 2. ACIDS Preservative is sodium propionate, ethyl paraben, and These include: chlorhexidine. o Boric acid Round or conical bottoms. o Hydrochloric acid o Acetic acid LESSON 2: TYPES OF URINE SPECIMENS o Tartaric acid Advantage: Prevents bacterial growth and metabolism. OVERVIEW Disadvantage: Interferes with analysis of drugs and hormones. To obtain a specimen that is representative of a patient’s Keeps pH at about 6.0 Can be used for transport of urine cultures. metabolic state, regulation of certain aspects of specimen collection is often necessary. 3. FORMALIN (FORMALDEHYDE) These special conditions may include time, length, and method Advantage: Excellent sediment preservative. of collection, as well as the patient’s dietary and medicinal intake. Disadvantage: Acts as a reducing agent, interfering with It is important to instruct patients when they must follow special chemical tests for glucose, blood, leukocyte esterase, and collection procedures. copper reduction. Rinse specimen container with formalin to preserve cells and RANDOM SPECIMEN casts. This is the specimen received most commonly because of its ease of collection and convenience for the patient. 4. SODIUM FLUORIDE It may be collected at any time, but the actual time of voiding Advantage: Good preservative for drug analyses. should be recorded on the container. Disadvantage: Inhibits reagent strip tests for glucose, blood, and It also useful for routine screening tests to detect obvious leukocytes. abnormalities. However, it also may show erroneous results resulting from dietary intake or physical activity just before collection. [AUBF Laboratory: Module 1 Discussion] FIRST MORNING SPECIMEN MIDSTREAM CLEAN-CATCH SPECIMEN Although it may require the patient to make an additional trip to As an alternative to the catheterized specimen, the midstream the laboratory, this is the ideal screening specimen. clean-catch specimen provides a safer, less traumatic method It is also essential for preventing false-negative pregnancy tests for obtaining urine for bacterial culture and routine urinalysis. and for evaluating orthostatic proteinuria. It provides a specimen that is less contaminated by epithelial It is a concentrated specimen, thereby assuring detection of cells and bacteria and therefore is more representative of the chemicals and formed elements that may not be present in a actual urine than the routinely voided specimen. dilute random specimen. Patients must be provided with appropriate cleansing materials, The patient should be instructed to collect the specimen a sterile container, and instructions for cleansing and voiding. immediately on arising and to deliver it to the laboratory within 2 Strong bacterial agents, such as hexachlorophene or povidone- hours or keep it refrigerated. iodine, should not be used as cleansing agents. Mild antiseptic towelettes are recommended; some urine 24-HOUR SPECIMEN (TIMED) collection transfer kits contain Castile Soap Towelettes. Measuring the exact amount of a urine chemical is often necessary instead of just reporting its presence or absence. SUPRAPUBIC ASPIRATION A carefully timed specimen must be used to produce accurate Occasionally urine may be collected by external introduction of quantitative results. a needle through the abdomen into the bladder. Many solutes exhibit diurnal variations such as: Because the bladder is sterile under normal conditions, o Catecholamines suprapubic aspiration provides a specimen for bacterial culture o 17-hydroxysteroids that is completely free of extraneous contamination, particularly o Electrolytes; lowest concentration is in the early morning in infants or children. and the highest concentration occurs in the afternoon. The specimen also can be used for cytological examination. When the concentration of the substance to be measured changes with diurnal variations and with daily activities, such as PROSTATITIS SPECIMEN exercise, meals, and body metabolism, 24-hour collection is Several methods are available to detect the presence of required. prostatitis. If the concentration of a particular substance remains constant, the specimen may be collected over a shorter period. THREE-GLASS COLLECTION Care must be taken, however, to keep the patient adequately Before collection, the area is cleansed using the male midstream hydrated during short collection periods. clean-catch procedure. (1st pass-out sterile container) Patients must be instructed on the procedure for collecting a Then, instead of discarding the first urine passed, it is collected in timed specimen. a sterile container. To obtain an accurate timed specimen, the patient must begin Next, the midstream portion is collected in another sterile and end the collection period with an empty bladder. container. (2nd midstream-sterile container) The concentration of a substance in a particular period must be Then the prostate is massaged so that prostate fluid will be calculated from the urine volume produced during that time. passed with the remaining urine into a third sterile container. (3rd On its arrival in the laboratory, a 24-hour specimen must be remaining urine) mixed thoroughly and the volume accurately measured and Quantitative cultures are performed on all specimens, and the recorded. first and third specimens are examined microscopically. If only an aliquot is needed for testing, the amount saved must In prostatic infection, the third specimen will have a white blood be adequate to permit repeat or additional testing. cell/high-power field count and a bacterial count 10 times that If a specimen is collected in two containers, the contents of the of the first specimen. containers should be combined and thoroughly mixed before Macrophages containing lipids also may be present. aliquoting. The second specimen is used as a control for bladder and Consideration also must be given to the preservation of kidney infection. specimens collected over extended periods. o If it is positive, the results from the third specimen are invalid All specimens should be refrigerated or kept on ice during the because infected urine has contaminated the specimen. collection period and may require addition of a chemical preservative. PRE-AND POST-MASSAGE TEST The preservative chosen must be nontoxic to the patient and In the pre- and post-massage test (PPMT), a clean-catch should not interfere with the tests to be performed. midstream urine specimen is collected. Appropriate collection information is included with test A second urine sample is collected after the prostate is procedures and should be read before issuing a container and massaged. instructions to the patient. A positive result is significant bacteriuria in the post-massage specimen of greater than 10 times the pre-massage count. COMMON ERRORS ASSOCIATED WITH TIMED COLLECTIONS Loss of urine specimen STAMEY-MEARES TEST FOR PROSTATITIS Inclusion of two first morning specimens The traditional four-glass urine collection technique, as Inaccurate measurement of total urine volume described by Meares and Stamey: Inadequate urine preservation 1. The first urine specimen is voided bladder (VB1), which is the first Transcription error 10 mL of urine and represents the urethral specimen. 2. Then the patient voids another 100 to 150 mL of urine. CATHETERIZED SPECIMEN 3. The second specimen, voided bladder 2 (VB2), is collected, which This specimen is collected under sterile conditions by passing a is another 10 mL of urine and represents the bladder specimen. hollow tube (catheter) through the urethra into the bladder. 4. The third specimen is the expressed prostatic specimen (EPS), Urine passes from the bladder through the catheter into a plastic which is the fluid collected during prostatic massage. bag, where it accumulates; urine specimens then can be 5. The fourth specimen, voided bladder 3 (VB3), consists of the first collected from this urine bag. 10 mL of urine collected after EPS; it contains any EPS trapped in Bacterial culture – most common test requested. the prostatic urethra. [AUBF Laboratory: Module 1 Discussion] 6. All four specimens are sent for culture. The urine temperature must be taken within 4 minutes from the 7. The three urine specimens are centrifuged, and the sediment is time of collection to confirm the specimen has not been examined for white blood cells/aggregates, macrophages, oval adulterated. fat bodies, bacteria, and fungal hypha. The temperature should read within the range of 32.5°C to 37.7°C. Urethral infection or inflammation is tested for by the VB1, and the o If the specimen temperature is not within range, the VB2 tests for urinary bladder infection. temperature should be recorded and the supervisor or The prostatic secretions are cultured and examined for white employer contacted immediately. blood cells. o Urine temperatures outside of the recommended range Having more than 10 to 20 white blood cells per high-power field may indicate specimen contamination. is considered abnormal. o Re-collection of a second specimen as soon as possible will be necessary. PEDIATRIC SPECIMEN The urine color is also inspected to identify any signs of Collection of pediatric specimens can present a challenge. contaminants. Soft, clear plastic bags are available for collecting routine The pH and specific gravity of the specimen also may be tested. specimens; these bags have hypoallergenic skin adhesive to A urine pH of greater than 9 suggests adulteration of the urine attach to the cleaned genital area of both boys and girls. specimen and requires that the specimen be re-collected if Sterile specimens may be obtained by catheterization or by clinically necessary. suprapubic aspiration. A specific gravity of less than 1.005 could indicate dilution of the Care must be taken not to touch the inside of the bag when urine specimen and requires re-collection. applying it to the patient’s skin. The specimen is labeled, packaged, and transported following laboratory-specific instructions. ROUTINE SPECIMEN ANALYSIS Ensure the area is free of contamination. ADDITIONAL TYPES OF URINE SPECIMEN Attach the bag firmly over the cleaned genital area, avoiding the 1. Fasting (Second Morning) – fasting specimen does not contain anus. any metabolites from ingested food. A diaper is placed over the collection bag. 2. 2-hour Post Prandial – patient’s void before consuming routine When enough specimen has been collected, remove the bag meal; collect specimen 2 hours after eating. and label it, or pour the specimen into a container and label the 3. Glucose Tolerance Test (GTT) – blood tests are correlated with container following facility policy. renal threshold for glucose. a. Number of specimens varies with the length of the test: MICROBIOLOGY SPECIMEN ANALYSIS i. Fasting Clean the area with soap and water and sterilely dry the area, ii. Half-hour removing any residual soap residue. iii. 1-hour Firmly apply a sterile bag. iv. 2-hour Sterilely transfer the collected specimen into a sterile container v. 3-hour and label the container. TYPES OF URINE SPECIMENS (SUMMARIZED) DRUG SPECIMEN COLLECTION Type of Specimen Purpose Urine specimen collection is the most vulnerable part of a drug- Random - Routine screening testing program. First morning - Routine screening Correct collection procedures and documentation are - Pregnancy tests necessary to ensure that the results are those of the specific - Orthostatic protein individual submitting the specimen. 24-hour (timed) - Quantitative chemical tests Chain of Custody (COC) – is the process that provides this - Hormones and electrolytes documentation of proper specimen identification from the time Catheterized - Bacterial culture of collection to the receipt of laboratory results. Midstream clean-catch - Routine screening o It is a standardized form that must document and - Bacterial culture accompany every step of drug testing, from collector to Suprapubic aspiration - Bladder-urine bacterial courier to laboratory to medical review officer to employer. culture For urine specimens to withstand legal scrutiny, it is necessary to - Cytologic examination prove that no tampering of the specimen occurred, such as Three-glass collection - Prostatic infection substitution, adulteration, or dilution. Four-glass collection - Prostatic infection All personnel handling the specimen must be noted. Fasting (second morning) - Diabetic The specimen must be handled securely, with a guarantee that screening/monitoring no unauthorized access to the specimen was possible. 2-hour post prandial - Monitoring insulin therapy in Proper identification of the individual whose information is DM persons indicated on the label is required. Glucose tolerance test - Optional with blood samples Either photo identification or positive identification by an - Glucose and ketones employer representative with photo ID is acceptable. WITNESS OR UNWITNESSED Urine specimen collections may be “witnessed” or “unwitnessed.” The decision to obtain a witnessed collection is indicated when it is suspected that the donor may alter or substitute the specimen or when it is the policy of the client ordering the test. If a witnessed specimen collection is ordered, a same-gender collector will observe the collection of 30 to 45 mL of urine. Witnessed and unwitnessed collections should be handed to the collector immediately.