chemical examination

• What is the first step in the pre-analytical phase of urine analysis?

  The site of the experiment should be sterilized.
• What personal protective equipment should a medical technologist wear before the experiment?

  Proper personal protective equipment.
• What should a medical technologist check upon receiving a urine specimen?

  If the urine container is properly labeled and records the information indicated.
• What materials are required for testing with reagent strips?

  • Freshly voided or random urine specimen
  • N-Multistix SG reagent strip
  • Two types of reagent strips: multistix and chemstrips
• What materials are required for testing with reagent tablets?

  • Freshly voided or random urine specimen
  • Clinitest Tablet
• What is the first step in the procedure for reagent strips?

  Completely immerse all reagent areas of the strip in fresh, well-mixed uncentrifuged urine and remove immediately.
• Why should the reagent strip be held in a horizontal position after immersion?

  To prevent possible mixing of chemicals from adjacent reagent areas and/or soiling of hands with urine.
• How should the test areas of the reagent strip be compared with the color charts?

  Hold the strip closely to color blocks and match carefully at the times specified.
• What should be used when performing the Clinitest?

  The accompanying test tube and dropper.
• What is the procedure for adding urine and water in the Clinitest?

  Add five drops of urine and then 10 drops of water into a clean, dry test tube.
• What should be done if a bright orange color appears during the Clinitest?

  Record as "over 2%" and do not compare with the color chart.
• How can sugar concentration above 2% be estimated?

  Dilute the urine being tested with normal urine and repeat the test, multiplying the results by dilution.
• What must a medical technologist do before leaving the laboratory?

  • Return materials, slides, and microscopes
  • Dispose of wastes and disinfect the area
  • Properly remove PPE without exposing it outside the laboratory
• What are the characteristics of reagent strips?

  • Provide a simple, rapid means for chemical analysis of urine
  • Consist of chemical-impregnated absorbent pads on a plastic strip
  • Require 10-15 mL of sample
• What parameters can be tested with a 4-parameter reagent strip?

  Glucose, protein, specific gravity, and pH.
• What additional parameters are included in a 10-parameter reagent strip?

  1. parameter plus bilirubin, ketones, blood, urobilinogen, nitrite, and leukocyte esterase.
• What is the significance of ascorbic acid in reagent strips?

  It causes false negative results with oxidizing principle tests.
• What can cause false positive results in reagent strip testing?

  Detergents.
• What can cause false negative results in reagent strip testing?

  Ascorbic acid and uric acid.
• What are the steps in the reagent strip technique?

  1. Dip the strip in well-mixed urine.
  2. Remove excess urine by touching the edge to the container.
  3. Blot the edge on an absorbent pad.
  4. Wait for the specified reaction time.
  5. Compare color reaction to the manufacturer's color chart.
• What errors can occur due to improper technique in reagent strip testing?

  Formed elements may sink, leaching of reagents, run-over between chemicals, timing variations, poor lighting, and using incompatible strips.
• Why is it important to allow refrigerated specimens to return to room temperature before testing?

  To ensure accurate results during reagent strip testing.
• How should reagent strips be stored?

  • With desiccant in an opaque, tightly closed container
  • Below 30°C; do not freeze
  • Avoid exposure to volatile fumes
  • Do not use past expiration date
  • Do not use if pads are discolored
• How often must reagent strips be checked with controls?

  A minimum of once every 24 hours.
• What is not recommended as a negative control for reagent strips?

  Distilled water.
• What are the parameters and their corresponding times for reagent strip testing?


  • Glucose: 30 secs
  • Bilirubin: 30 secs
  • Ketone: 40 secs
  • Specific gravity: 45 secs
  • pH: 60 secs
  • Protein: 60 secs
  • Blood: 60 secs
  • Urobilinogen: 60 secs
  • Nitrite: 60 secs
  • Leukocyte: 120 secs
  • Ascorbic Acid: C-stix: 10 secs, Stix: 60 secs
• What is the principle of the automated strip reader?

  It has an inverse relationship between light color and light reflection.
• What is the purpose of confirmatory testing?

  To provide greater sensitivity than reagent strip testing.
• What is the principle of the Clinitest?

  Copper reduction test.
• What sugars can be tested with Clinitest?

  All sugars except for sucrose.
• What is the major component of the Clinitest tablet?

  CuSO4.
• What is the pass-through phenomenon in Clinitest?

  Occurs when >2 g/dL sugar is present.
• What is the procedure for the Acetest?

  1. Remove the Acetest tablet and place on white paper.
  2. Place 1 drop of urine on the tablet.
  3. Wait 30 seconds.
  4. Compare the tablet color with the color chart.
  5. Report as negative, small, moderate, or large.
• What is the purpose of the ICTOTEST?

  It is a confirmatory test for bilirubin.
• What is the sensitivity of the ICTOTEST compared to reagent strips?

  More sensitive than reagent strips.
• What are the steps in the ICTOTEST procedure?

  1. Place 10 drops of urine on the absorbent test mat.
  2. Use forceps to place the Ictotest tablet in the center.
  3. Add 1 drop of water on the tablet and wait 5 seconds.
  4. Add a second drop of water to run off the tablet onto the mat.
  5. Observe the color of the mat after 60 seconds.
• What are the parameters and reagents for urine analysis?

  • pH: Methyl red, Bromthymol blue
  • Protein: Tetrabromophenol blue
  • Glucose: Glucose oxidase, Peroxidase
  • Ketone: Sodium nitroprusside
  • Blood: Diisopropylbenzene dihydroperoxide
  • Bilirubin: 2,4-dichloroaniline diazonium salt
  • Urobilinogen: p-dimethylaminobenzaldehyde
  • Nitrite: p-arsanilic acid
  • Leukocyte Esterase: Derivatized pyrrole amino acid ester
  • Specific Gravity: Poly (methyl vinyl ether/maleic anhydride)
• What is the sensitivity range for Multistix pH testing?

  1. 0 to 8.5 in 0.5 increments.
• What is the sensitivity for Chemstrip pH testing?

  1. 0 to 9.0 in 1.0 increments.
• What is the sensitivity for Multistix protein testing?

  15 to 30 mg/dL albumin.