Prelab Preparation

Artificial urine can be altered to create many simulated urinalysis tests. Use the “normal” artificial urine and the recipes that follow to create unknown individuals with various anomalies. Determine which tests will be conducted by students and how many unknown individuals they will be testing. Mix all the “unknown” urines prior to the lab. Secure all materials necessary for the urinalysis tests. Create direction sheets and worksheets as appropriate for the urinalysis procedures used. See the Tips section for some suggestions. Complete urinalysis kits are also available from Flinn Scientific. See listing at the end of this publication.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. All materials can be disposed of following Flinn Suggested Disposal Method #26b.

Teacher Tips

• The number of factors or tests you will conduct in your urinalysis lab will be dependent upon the course you are teaching, its goals and your student population. The basic simulated “normal” urine solution in this kit will expedite building a lab exercise to fit your unique teaching situation.

• The 1 L of “normal” urine solution will yield many test results since most tests require only drops to complete. Divide the 1 L of solution into appropriately sized samples for each of the “unknown” urine samples in your lab.
• A logical sequence of lab development might include these steps:
  1. Choose the factors to be tested from those outlined in the Procedure section.
  2. Determine the number of urine samples students will test (i.e., outline the nature and number of the “unknown” urine samples).
  3. Create student record sheets with procedural directions for each test. Incorporate the number of unknown individuals and the tests to be conducted into the worksheet.
  4. Prepare the “unknown” urine samples and store in appropriate bottles. (Be sure to use “normal” urine for one of the unknown individuals to serve as a control for all tests.)
  5. Locate all the necessary testing materials.
  6. Run prelab tests for all of the “unknown” individuals to be sure they yield the results expected.
  7. Finalize worksheets and make copies.
  8. Organize lab test stations with all necessary test materials.
  9. Orchestrate the lab.
  10. Conduct post-lab discussion and urinalysis of each unknown individual discussing possible anomalies indicated by the test results.

• Conduct this simulated lab like a real medical lab training situation. Remind students that they are handling urine specimens and they will likely respond as if they are real!
• Fluorescein can be added to the urine samples. At the end of the lab a darkened room and a UV light will reveal how carefully students have conducted the tests and where “urine” has been spread in the laboratory. This will likely prompt a thorough cleanup of the laboratory.

References

Shmaefsky, B. R., The American Biology Teacher, 1995, Vol. 57, No. 7.

Tietz, N. W., editor, Fundamentals of Clinical Chemistry, W. B. Saunders, Philadelphia, 1976.

Introduction

Safely learn the basics of urinalysis using artificial urine. Eliminate all the potential problems associated with handling real body fluids in the classroom.

Concepts

• Urinalysis

Background

The fear of contracting contagious microbial agents through body fluids has led to the near elimination of their use in public classrooms. Elimination of the clinical testing of body fluids from an anatomy and physiology curriculum is not recommended since students should be familiar with all the valuable information that can be obtained through the clinical testing of body fluids. Becoming familiar with the safe handling procedures of contagious materials before taking a job in the health sciences field is also a side benefit. The use of artificial urine can allow the practice of standard urinalysis procedures in the classroom without the fear of health problems.

The materials and suggestions provided with this safe set of materials will allow the creation of “unknown” individuals and realistic urinalysis simulations often encountered in a medical laboratory.

Materials

Safety Precautions

Although no actual body materials are included in the artificial urine, “simulated” body fluid laboratory exercises should be conducted as if the fluids were real body fluids. Therefore, chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron should be worn. Working areas should be scrubbed with a mild bleach solution before and after urinalysis procedures. Wash hands thoroughly with soap and water before leaving the laboratory.

Procedure

1. Glycosuria—Urine normally contains such small amounts of glucose that glucose is clinically considered to be absent in “normal” urine samples. The “normal” artificial urine in this kit contains no glucose. The presence of glucose in significant amounts is called glycosuria. The most common cause of high blood sugar level (reflected in the urine) is a result of certain diseases, such as diabetes mellitus. Other conditions, such as pregnancy, excessive strain, renal tube damage or brain damage, may also result in elevated glucose in the urine.

Preparation: A moderate to high level of glycosuria can be achieved by adding glucose at 0.25–0.50 g/100 mL of “normal” urine solution.

Testing Procedure: Use glucose test strips to determine the glucose concentration in each urine sample or just test for the presence of glucose with Benedict’s solution.

2. Salt Crystals—The major salt crystals found in urine are calcium carbonate, calcium oxalate, calcium phosphate, hippuric acid, magnesium ammonium phosphate and uric acid. All of these salts form water insoluble precipitates and cause urinary tract problems. At concentrations of 0.05 g/100 mL the crystals start to form in the urine.

Preparation: Add 0.10 g/100 mL of a crystal additive (see above) to the “normal” urine solution.

Testing Procedure: A small sample should be centrifuged in a microcentrifuge tube, and a sample taken from the bottom of the tube and examined with a light microscope. Salt crystals should be visible with a microscope with reduced light.

3. Proteinuria—Protein is normally absent in “normal” urine. High levels of protein in the urine are an indicator of glomerular damage. Elevated urine protein may also result from excessive exercise, cold exposure, and acute abdominal diseases.

Preparation: Severe renal damage can be shown by adding albumen at 0.1 g/100 mL of “normal” urine solution.

Testing Procedure: Use Biuret test solution to test for protein in the urine samples. Place 5 mL of urine sample in a clean test tube. Add 2.5 mL of Biuret solution. Allow to set for 30 minutes and compare to original Biuret color. (The solution should turn from blue to pink.)

4. pH Imbalances—The normal pH of urine ranges from 4.6 to 8.0 and averages about 6.0. The pH of urine is strongly affected by diet. High protein diets cause a lowering of the pH and a mostly vegetable diet will increase the pH of the urine. Consistent acidic urine is a sign of metabolic acidosis, methanol poisoning or other metabolic disorders. Metabolism of fats produces more acid residue than the metabolism of carbohydrates. Starvation or excessive dieting and the resulting utilization of stored body fat will also produce ketosis and acidic urine.

Preparation: Acid urine can be simulated by adjusting the pH of the “normal” urine solution to a pH of 4.0 to 4.5 with 1 M HCl. (Add slowly, it will only require about 1 mL/100 mL of urine.) Alkaline urine can be obtained by adjusting the pH of the “normal” urine solution to a pH of 8 or 9 using 1 M NaOH. (Add slowly, it will only require about 1 mL/100 mL of urine.)

Testing Procedure: Use pH paper or other pH testing device to test urine samples.

5. Hyposthernuria—The specific gravity of urine depends on the amounts of solids in solution. “Normal” urine specific gravity ranges from 1.001 to 1.035. In certain conditions, such as diabetes mellitus, specific gravity is high because of the high glucose content. Consistently dilute urine, with a specific gravity less than 1.015, is an indication of cardiovascular problems, diabetes insipidous or renal tube problems.

Preparation: The specific gravity of the “normal” urine solution can be lowered by adding distilled water until the specific gravity approaches 1.000. Add the water slowly while using a urine hydrometer.

Testing Procedure: Test the specific gravity of urine with a urine hydrometer and hydrometer flask.

6. Color—Normal urine usually varies between a straw yellow and a clear amber color. Bright yellow urine is often an indication of dehydration or lack of water in the body. Urine is often rated for color on a scale as follows:

4 = Bright yellow
3 = Yellow
2 = Clear amber
1 = Nearly clear

Preparation: Add yellow food coloring one drop at a time to achieve a variety of colors in your unknown samples.

Testing Procedure: Visual examination and comparison of colors will reveal variations.

7. Odor—If simulated urine odor is desired, a variety of items can be added to the “normal” urine solution to achieve different odors.

Preparation: Onion and garlic extracts (grind a small amount in mortar and pestle) in small quantity impart a strong urine-type smell to the unknown samples. A small grain of dried yeast can create the odor of natural urine.

Testing Procedure: Chemical wafting can reveal odors of solutions.

8. Epithelial Cells—Normal urine contains some epithelial cells. An excess may indicate kidney injury or other internal abnormal conditions.

Preparation: Epithelial cells from fetal pig or cat dissection specimens serve as suitable/safe replacements for cells from the urogenital system. Cell yields vary a lot and practice will determine how much tissue to add to a 100 mL sample of normal urine. Shave the side and back surfaces of a young fetal pig or take shavings from the mouth of a preserved cat specimen. Tease and macerate the tissue and suspend it in the “normal” urine solution.

Testing Procedure: Add more tissue until the desired number of cells are found during microscopic examination.

9. Red Blood Cells—Red blood cells in the urine are a sign of many possible anomalies.

Preparation: Red blood cells from cattle, sheep or other available organisms can be used. Lyophilized blood cells are probably the safest and can be added to the sample.

Testing Procedure: Add enough red blood cells until they are visible during microscopic examination.