Lesson 6 — The Pancreas


 

Lab - Urinalysis


Introduction

Klingons are humanoid aliens, hailing from the planet Qo’noS in the Omega Leonis Star System. Although they share many physiological similarities with human species, they are known for being physically stronger, having a better immune system, and being able to maintain incredibly high metabolism. You are part of a group of Earth scientists who are commissioned to study the Klingon physiology.

From past studies, Earth scientists have concluded that Klingons are affected by the same types of human endocrine disorders. However, it has been noted that Klingons are capable of maintaining higher blood glucose levels than humans in order to sustain higher metabolism and maintain their complex organ systems.

You are provided with five urine samples from five Klingon patients. Your task is to perform an experiment to test the urine and blood samples to determine which of the five Klingon patients has
  • no endocrine disorder (healthy)
  • diabetes mellitus (Type 1)
  • diabetes mellitus (Type 2)
  • diabetes insipidus
  • Addison’s disease


Part A: General Observation

Here is a general description of the five Klingon patients’ urine samples. Read each statement and make appropriate notes in your results table below.

Sample A

  • clear, yellow solution
  • 24-hour urine output: 6 L 

Sample B

  • clear, yellow solution
  • 24-hour urine output: 8 L
  • urine smells sweet

Sample C

  • clear, yellow solution
  • 24-hour urine output: 8 L
  • urine smells sweet

Sample D

  • clear, yellow solution
  • 24-hour urine output: 2 L

Sample E

  • Clear, very pale yellow solution
  • 24-hour urine output: 10 L


Part B: Testing for Glucose in Urine Samples
Benedict’s solution is a clear, blue solution. It is used to test for the presence of glucose by observing a colour change. Benedict’s solution will change colour according to different levels of glucose in a given sample. No glucose should be present in urine samples of healthy individuals who are not affected with diabetes.

  1. Prepare a warm water bath by filling a large beaker about â…” full. Use a hot plate to warm the water up.
  2. Obtain six test tubes and mark them A, B, C, D, E, and control.
  3. Add 15 mL of the urine samples to the appropriately marked test tubes.
  4. Add 15 mL of distilled water to the control test tube.
  5. Add 5 mL of Benedict’s reagent to all six test tubes.
  6. Place the test tubes in the warm water bath for 15 minutes.
  7. After 15 minutes, record the colour change in the test tubes.


Record the following results in your data table below.

Sample Control A B C D E
Colour Blue
Blue
Olive green Olive green Blue Blue

Image 1. Benedict's Solution Colour Chart for Sugar Concentration.


Part C: Testing for Glucose in Blood Samples

Some glucose should be present in blood samples of healthy individuals. Higher than normal glucose concentrations would be observed in individuals with diabetes mellitus.

  1. Prepare a warm water bath by filling a large beaker about â…” full. Use a hot plate to warm the water up.
  2. Obtain six test tubes and mark them A, B, C, D, E, and control.
  3. Add 5 drops of the blood samples to the appropriately marked test tubes.
  4. Add 5 drops of distilled water to the control test tube.
  5. Add 5 mL of Benedict’s reagent to all six test tubes.
  6. Place the test tubes in the warm water bath for 15 minutes. After 15 minutes, record the colour change in the test tubes.


Record the following results in your data table below.

Sample Control A B C D E
Colour Blue
Light green
Orange   
 Orange  
 Light green
Light green


Image 1. Benedict's Solution Colour Chart for Sugar Concentration.



Part D: Testing for Ketone in Urine Samples
A test strip is dipped into the urine sample to detect the presence of ketone. A negative test is normal. When ketone is detected in a urine sample, it indicates that the body is using fat as the source of energy due to shortage of glucose. It is commonly seen in Type 1 diabetes.

 Record the following results in your data table below.

Sample Control A B C D E
Colour Pale pink
Pale pink
Pale pink Burgundy Pale pink Pale pink
 
Image 2. Ketone Test Strip Colours.


Part E: Testing for Sodium in Urine Samples
The presence of sodium can be detected by burning the sample and observing the colour of the flame. Sodium ions produce a bright orange flame. Light a bunsen burner. Dip a cotton swab in one of the urine samples. Place the cotton swab in the flame. Record the flame colour.

Record the following results in your data table below.

Sample Control A B C D E
Colour Blue
Orange
Blue Blue Blue Blue

 
Image 3. Flame test showing the presence of sodium.
Getty Images



Observation Table

Patient Observation Glucose (Urine)
Glucose (Blood)
Sodium
Ketone
Control
A
B
C
D
E


Analysis
Determine the conditions of the five patients. 

Conclusion
Why are glucose levels lower in urine than in blood?

Analysis
Control — No glucose present, no sodium, no ketone

Sample A—Addison’s disease
  • Higher than normal volume of urine was produced
  • No glucose was detected in the urine sample
  • Low glucose concentration was detected in the blood sample
  • Negative ketone test
  • Positive sodium test, indicating that the body may be producing lower than normal amount of aldosterone, resulting in higher amount of sodium released in the kidneys
Sample B—Diabetes mellitus (Type 2)
  • Sweet smelling urine was produced at high volume
  • Higher than normal glucose concentration was detected in the urine sample
  • Higher than normal glucose concentration was detected in the blood sample
  • Negative ketone and sodium tests
Sample C—Diabetes mellitus (Type 1)
  • Sweet smelling urine was produced at high volume
  • Higher than normal glucose concentration was detected in the urine sample
  • Higher than normal glucose concentration was detected in the blood sample
  • Ketone test was positive, indicating that the body is using fat as the source of energy
Sample D—Healthy
  • No glucose was detected in the urine sample
  • Low glucose concentration was detected in the blood sample
  • Ketone and sodium tests were negative
  • Normal amount of urine was produced
Sample E—Diabetes insipidus
  • No glucose was detected in the urine sample
  • Low glucose concentration was detected int he blood sample
  • Ketone and sodium tests were negative
  • High volume of dilute urine was produced, indicating that the pituitary gland may be producing lower than normal amount of ADH
Conclusion

Recall from Biology 20 that when the kidney filters blood, glucose from the blood goes into nephrons and is reabsorbed back into the blood as the filtrate travels through the nephron.  In individuals who do NOT have diabetis mellitus, all glucose in the filtrate is reabsorbed back into the blood so no glucose goes into the urine.  In individuals with untreated diabetis mellitus with higher than normal blood glucose levels, some glucose is reabsorbed.  However, the kidneys are unable to reabsorb all the glucose in the filtrate and some ends up in the urine.  The higher the concentration of glucose in the blood, the higher the level of glucose that ends up in the urine.