URINALYSIS part II

Chemical Examination

• Used to assist in the diagnosis of:

  • Kidney function

  • Urinary tract infections (UTIs)

  • Carbohydrate metabolism (diabetes mellitus)

  • Liver function

• Substances present in excess(abnormal) amounts in the blood are usually removed by urine

  • Example: glucose is normally present in the blood, if exceeds a certain level: excess is excreted in urine. (NEVER glucose in urine)

• Detection of substances that do not normally appear in the absence of disease.

  • Example: blood and nitrite

• Chemical tests that are routinely performed:

  • pH, Glucose, Protein, and Ketones.

• Other tests that may be performed:

  • Blood, Bilirubin, Urobilinogen, Nitrite, and Leukocytes.

• Qualitative tests (an approximate)

  • Indicate whether a substance is present in urine, and provide an approximate indication of the amount of substance present.

  • Interpretation of results, usually involves the use of color comparison chart. Results recorded in terms of:

    • Trace, 1+, 2+, 3+

    • Trace, small, moderate and large

    • Positive/Negative.

  • Useful for screening and easy to perform,

• Quantitative tests(giving a number)

  • Indicates the exact amount of chemical substance present in the body. results reported in measurable units. Example: 14 mg/dl

  • Usually involves use of complex equipment and testing procedures. Not usually performed in the medical office.

Urine Testing Kits

• Most frequently used in the medical office for chemical testing of urine.

  Advantages

  • Contain premeasured reagents.

  • Easy to perform and provide immediate results.

  • Most are qualitative test results: positive result indicates need for further testing.

  • Most manufactured in the form of reagent strips.

  • Relay on color change for interpretation of results. Test strips that contain more than one reagent may require different time intervals for reading results.

  • Certain meds may affect results, the expiration date must be checked before using.

  • Should not be used if color change has occurred on strip or tested strip is a color that does not match the chart.

  • Light, heat, and moisture can affect strips. Store in a cool, dry area, and package the tests in a light-resistant container.

  • Never transfer from original container to another may contain moisture, dirt, or chemicals. Indicate brand name of test that was used(e.g. Multistix 10SG)

Chemical Examination Types of Chemical Tests

pH

Unit that indicates acidity or alkalinity of a solution. Range of pH scale: 0.0 to 14.0.

• Neutral: 7.0

• Acid: below 7

• Alkaline: above 7

  Perform a test on freshly voided urine. If urine is allowed to stand out becomes more alkaline: urea is converted to ammonia by bacteria and pH goes up.

  pH of urine pH ranges from: 4.6 to 8.0, usually around 6.0(acidic)

• High reading on a fresh specimen(e.g. alkaline urine) may indicate bacterial infection of the urinary tract.

  Glucose

  Should not normally be present in urine.

• Glucose in blood: filtered through nephrons and reabsorbed into the body. If glucose concentration in the blood becomes too high: renal threshold is exceeded. Kidneys are unable to reabsorb all of glucose back into the blood. Results in glycosuria: glucose in urine.

• Renal threshold: concentration at which a substance in the blood not normally excreted by the kidney begins to appear in the urine. Renal threshold for glucose is generally 160 to 180 mg/dl.

• Diabetes most common cause of glycosuria.

• Alimentary glucosuria a patient has a low renal threshold, glucose may appear after consumption of large quantities of sugar.

Protein

• Proteinuria: Presence of protein in the urine/it’s not normal. Temporary increases may be caused by stress or strenuous exercise. Conditions causing proteinuria are glomerular filtration problems, renal diseases, and bacterial infections of urinary tract. If proteinuria occurs physician usually orders an examination of sediment to see what is causing the protein to be in the patient’s urine(e.g. bacteria).

Ketones

Three types of ketone bodies

• β-Hydroxybutyric acid, Acetoacetic acid, and Acetone.

Normal products of fat metabolism can be used by muscle tissue as a source of energy. When more than normal amounts of fat are metabolized muscles cannot handle all of the ketones that result

Ketosis: accumulation of large amounts of ketone bodies in tissue and body fluids.

ketonuria: the presence of ketone bodies in the urine(body rids itself of excess ketones by excreting them in urine).

• Conditions causing ketonuria are uncontrolled diabetes, starvation, and a diet composed almost entirely of fat.

Bilirubin

• Life span of RBC: 120 days. RBC contains hemoglobin, their function is to transport oxygen in the body. When RBC breaks down, hemoglobin breaks down and releases bilirubin(vivid yellow pigment). Bilirubin is normally transported to liver and excreted with bile to digest fat that eventually leaves the body through the intestines(feces) with certain liver conditions, the liver cannot accept bilirubin.

• Bilirubin transported to kidneys. Excreted into urine: bilirubinuria that causes urine to be yellow-brown or greenish.

• Conditions causing biliribinuria are gallstones, hepatitis, and cirrhosis of the liver.

Urobilinogen

• Condition causing an increase in urobilinogen in the urine. Excessive hemolysis of red blood cells, infectious hepatitis, cirrhosis, CHF, and mononucleosis.

Blood

• Considered abnormal(unless resulting from menstruation). Hematuria is the presence of blood in urine. Conditions causing hematuria are injury, cystitis, tumors of the bladder, urethritis, kidney stones, and certain kidney disorders.

Nitrite

• Indicates the presence of a pathogen in the urinary tract. Pathogens present in the urine in the bladder cause nitrate to convert to nitrite.

  • Nitrate: normally present in urine.

* Nitrite: normally absent in the urine.

• Perform on urine that has been in the bladder for 4 to 6 hrs(first voided specimen) to ensure the pathogens have converted nitrate to nitrite. Should not be performed on specimen that has been standing out because results in a false-positive result due to environmental bacteria contamination of the specimen.

• Screening test usually followed with culture.

Leukocyte

Leukocyturia: Presence of leukocytes in the urine. Accompanies inflammation of kidneys and lower urinary tract. Conditions causing leukocyturia are acute and chronic pyelonephritis, cystitis, and urethritis.

• Recommended specimen for women, clean catch midstream collection, prevents contamination of specimen with leukocytes from vaginal secretions.

Chemical Examination Reagent Strips

Disposable plastic strips contain reagent areas for testing chemicals in urine. Results provide physicians with information to assist in the diagnosis of kidney function conditions (e.g. kidney stones), UTI, Carbohydrate metabolism conditions, liver function conditions, acid-base balance of the body, and urine concentration. Provide qualitative test results.

Chemical Examination Guidelines for Reagent Strip Urine Testing

1. Preferred type of specimen: Freshly voided and thoroughly mixed. if not possible, refrigerate the specimen. Before testing, allow to return to room temperature and thoroughly mix the specimen.

2. 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

3. Specimen container, must be clean to prevent inaccurate test results and must be large enough to allow for complete immersion of strip.

4. Time Intervals, read results at exact time intervals specified on color chart. Do not read any test results after 2 min.

5. Interpretation of results, compare with color chart in good lighting.

6. Storage of reagent strips: cool, dry area with the cap tightly closed. The reagents on strips are sensitive to light, heat, and moisture. The container includes a desiccant to absorb moisture(don’t remove it). 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.

   • Ensures reliability of test results. Example: Check-stix control checks reliability of Multistix. Consists of a plastic strip with seven synthetic ingredients. The reconstituted solution is tested with a Multistix reagent strip. 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, outdated strips or control, improper storage of strips or control, and error in technique.

Chemical Examination Urine Analyzer

Performs chemical examination of urine automatically by using reagent strips. Advantage: quick and easy, results are interpreted automatically.

Microscopic Examination of Urine

First voided morning specimen preferred: more concentrated. Important to use a fresh specimen, changes might occur if a specimen is left standing out. MA is responsible for preparing urine specimens.

• Urine Sediment:

  • Solid materials contained in urine, sediment sample placed on a slide by MA. Viewed under a microscope by a physician to help to clarify results of the physical and chemical examination.

• Red Blood Cells:

  • Round, colorless, and biconcave discs. Normal range: 0-5 per high-power field; more than 5 per high-power field may indicate bleeding along the urinary tract.

  • Concentrated urine: causes RBCs to become shrunken or crenated.

  • Dilute urine causes RBCs to swell and hemolyze. Cannot be seen under a microscope. Still show a positive result on reagent strip test(blood).

• White Blood Cells:

  • Round, granular, and have a nucleus. Approximately 1.5 times larger than RBCs.

  • Normal: 0 to 8 per high-power field. More than 8 per high-power field may indicate inflammation of the genitourinary tract.

  • If we see up to 8 is called lisaturia.

• Epithelial Cells:

  • Most structures making up the urinary system, composed of several layers of epithelial cells.

    - Outer layer: constantly being sloughed off or replaced by cells underneath.

  • Squamous epithelial cells: large, clear, fat cells with irregular shape that contain a small nucleus, come from urethra, bladder, or vagina. Normally present in small amounts in urine.

  • Renal epithelial cells: Round with large nucleus. Come from deeper layers of the urinary tract, it’s presence in urine is abnormal.

• Casts:

  • Cylindrical structures: formed in the lumen of nephron tubules. Materials in tubules harden are flushed out: appear in urine as casts. Generally indicate diseased condition.

  • Named according to what they contain

    - Hyaline casts: Pale, colorless cylinders with rounded edges.

    - Granular casts: Hyaline casts that contain granules.

    - Fatty casts: Hyaline casts that contain fat droplets.

    - Waxy casts: Light yellowish with serrated edges.

    - Cellular casts: Hyaline casts that contain organized structures.

    • Named for what they contain: RBC casts, WBC casts, Epithelial casts, Bacterial casts.

• Crystals:

  • Variety may be found in urine. Type and number vary with urine pH. Abnormal crystals are leucine, tyrosine, and cystine.

• Miscellaneous Structures

  • Mucous threads: Normally present in small amounts in urine. Are long, wavy, threadlike structures with pointed ends.

  • Bacteria: Rod-shaped or round. Should not normally be present. The presence of more than a few may indicate contamination of specimen during collection, or UTI.

  • Yeast cells: Smooth, refractile bodies with an oval shape, small buds project from cells, and in females usually vaginal contaminant caused by candida albicans (yeast infection).

  • Parasites: May be present as a contaminate from fecal or vaginal material. Trichomonas vaginalis a parasite that causes trichomoniasis vaginitis.

  • Spermatozoa: May be present in men or women after intercourse. It has round heads and long, slender, hairlike tails.

Rapid Urine Cultures

Assist in the diagnosis of UTI and assessment of the effectiveness of antibiotic therapy for UTI. Consists of a slide attached to a screw cap, each side of the slide is coated with agar medium, suitable for growth of urinary bacteria.

• Don’t use if agar is dehydrated, or if mold or bacterial growth is present.

• Slide suspended in clean plastic vial: protects it from contaminants.

• Recommended urine specimen: clean-catch midstream. Collected after urine has been in bladder for 4 to 6 hours. The slide is dipped into the urine specimen, then slide is incubated, and compared with a reference chart.

Urine Pregnancy Testing

Immunologic tests are often used in office. Test results rely on the presence of human chorionic gonadotropin(HCG). Concentrated urine specimen required(first-voided morning).

• Purpose: To determine if a woman is pregnant before certain medications are given or procedures are performed that may cause injury to a fetus.

Human Chorionic Gonadotropin

Produce by developing fertilized egg immediately after conception and implantation: level of HCG rises rapidly. Small amounts secreted into urine and blood, can detect pregnancy with a serum pregnancy test as early as 6 days before the first missed period.

• High level: occurs 8 weeks after conception. After this time HCG declines.

• 72 hours after delivery: HCG disappears entirely.

• Pregnancy tests are more sensitive in the first trimester.

• May even show a negative reaction during second and third trimester.

HCG Immunoassay Test

• Used in a medical office to detect pregnancy.

• Provide immediate test results.

• Positive and negative reactions result in specific visible reactions.

• Commercially available in testing kits.

• Most are 99% accurate with a low occurrence of false positive test results.

• Brand names are QuickVue One Step, OSOM, and Clearview.

• Early prediction U pregnancy test, as early as 2-3 days before the missed period, may sometimes show a false-negative result when performed early.

• Accurate results are more probable if urine is tested 1 week after a missed period.

• Conditions that can result in a positive result other than normal pregnancy are ectopic pregnancy or molar pregnancy.

Guidelines for Urine Pregnancy Testing

Use clean disposable urine containers

• Preferred specimen: First-voided morning specimen, contains the highest concentration of HCG. However, a random specimen can be used.

• Specific gravity should be determined before a test. Less than 1.007 is too dilute for testing could cause a false-negative result.

• Urine specimens should be at room temperature.

• Kit should be stored according to information in the product insert. Most testing kits are stored at RT between 59°F(15°C) and 86°F(30°C) and away from direct sunlight.

• Check expiration date

• Most testing kits include an internal control. Performed at the same time as testing procedure. Determines whether a sufficient amount of specimen was added to cassette, or if correct technique was followed. Document internal control in quality control log for first test run each day.

• External controls: Consist of commercially available solutions. May be included with test system or may need to be purchased separately.

  • Perform a positive and negative external control with each new lot of urine pregnancy testing kits monthly thereafter.

  • External controls are used to, determine if testing reagents are performing properly or to detect any errors in technique.

• Control Procedure: Instead of adding a patient specimen to testing device add a control solution.

  • Positive control: should produce a positive result.

  • Negative control: should produce a negative result.

  • Document results

  • Failure of external control to produce expected results may be due to deterioration of testing components due to improper storage.

Serum Pregnancy Test

Radioimmunoassay(RIA) for HCG: Used to detect HCG in the serum of blood. More sensitive than urine testing, can detect pregnancy earlier with more accuracy. Can detect pregnancy at approximately the eighth day after fertilization, 6 days before the first missed period.

• Uses radioisotope technique, capable of detecting minute amounts of HCG in the blood.

• It’s used to diagnose abnormalities like ectopic pregnancy. Follow the course of early pregnancy when abnormalities of embryonic development are suspected. Provide early diagnosis of pregnancy in high-risk patients, Example: patients with diabetes mellitus.