Urine Analysis

What's it all about?

Doctors can learn a lot about a patient from their urine, for example, whether the patient has kidney disease or diabetes, or if they are abusing drugs. Experience shows that when students are introduced to this activity, they are either alarmingly keen to produce urine samples, or desperately keen to avoid doing so!

So, to avoid such worries, some simple chemistry can be used to mimic the look and (amazingly) the smell of urine for some tests. It really does look convincing, especially when our technicians Carol and Malcolm bring out brimming litre containers! We find that once the students are clear about how the samples were produced, they really enjoy the activity and look forward to telling their parents all about it later! The tests are for colour and odour, pH, and the presence or absence of protein and glucose.
 

What is here?

You can:

Download the Acrobat file on this topic (217K - this identical to the one we use, including the students’ worksheet in colour), or

View the notes below. These are divided into:
Student notes
Teacher notes
Technician notes

Student notes

There are four tests to do on each samples of urine: examination by eye and nose, protein testing, pH testing and glucose testing.

The Scene

A dastardly crime has been committed in the vicinity of the toilets. The villain’s urine and samples from four suspects has been collected. Your task is to find out who did it. Carry out the tests below on Sample 0 to make sure you can carry out all the tests properly, then repeat them for Samples 1 to 4 and the villain’s sample.

Examination by eye and nose

Examine the urine carefully by eye and ... nose! Comment on the colour of the urine. Try to use words like yellow, amber, dark and pale. Examine the sample for its odour (smell). Also note whether the sample is clear or cloudy. Note your observations in your Piddle Chart.

Test for protein

Next, find out if the sample contains protein (protein leaks into the urine if the kidneys are damaged). Divide the sample equally between two test tubes. Put one tube into the hot water bath, and leave the other at room temperature. After a few minutes, take the test tube out of the water bath, and compare the heated and unheated urine. If the heated sample is more cloudy, it contains protein. Note your result in your Piddle Chart. Flush away the heated urine, and keep the unheated sample.

pH testing

Now you need to find out the pH of the unheated urine. Dip a piece of universal indicator paper into the urine. Quickly take it out, and leave it for 30 seconds. Compare the new colour with the pH colour chart, and note the pH number on your Piddle Chart.

Testing for glucose

The last test is to find out if the urine contains glucose, which may indicate that the patient has diabetes. Dip a Clinistix into the unheated urine sample, and immediately take it out. Count to ten, then check the colour with the colour chart. Record whether the urine is negative, light, medium or dark (dark means a lot of glucose).

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Piddle Chart

Record your results for Sample 0 in the table below.
 

Colour
Odour
Unheated
Heated
Universal indicator
pH
Clinistix result

Record your results for Samples 1 to 4, and the villain’s sample, in the table below.
 

	Sample 1	Sample 2	Sample 3	Sample 4	Villain
Colour
Odour
Protein?
pH
Glucose?

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Teacher notes

There is a fair amount of excitement involved in this activity, so we find that it is important to impress upon the students that they should treat the samples following normal laboratory rules. The identity of the villain can be changed if you run the activity more than once. We find that it is easy for the students to distinguish between the samples listed below, but you could make up other combinations. The protein test works well, but you might want to use the biuret test instead. We use Bayer Diagnostics Clinistix strips to test for glucose. These are easy to use, and give the activity an authentic feel. However, you may wish to use Benedict’s reagent instead (and you could use the hot water bath to heat the samples instead of using Bunsen burners).

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Technician notes

For 5 groups of students:

5 x teat pipettes
5 x test tube racks
10 x test tubes (or boiling tubes)

Labelled water bath set at 70°C with test tube rack
Universal indicator paper with colour charts
Bayer Diagnostics Clinistix glucose test strips with colour charts

Artificial urine samples:

Sample 0
Dissolve 3g sodium chloride, 5g urea, 1g glucose powder and 1g albumin powder in 1dm³ water. Add 1 drop of 2M hydrochloric acid.

Sample 1
Dissolve 3g sodium chloride, 5g urea and 1g glucose powder in 1dm³ water. Add 3 drops of 2M hydrochloric acid.

Sample 2
Dissolve 3g sodium chloride and 1g glucose powder in 1dm³ water. Add 3cm³ of 1M ammonia solution.

Sample 3
Dissolve 3g sodium chloride, 5g urea and 1g albumin powder in 1dm³ water.

Sample 4
Dissolve 3g sodium chloride, 1g glucose powder and 1g albumin powder in 1dm³ water.

Villain sample
Select one of Samples 1 to 4.

Note: You may wish to add some yellow food colouring to enhance the appearance of the samples.

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