Test For Presence Of Sugar In Urine: Purpose, Procedure, And Results

The urine sugar test is one of the many common diagnostic methods used for the test of sugar presence in urine, which would further be an indicator of diabetes or some other conditions. It tests for the amount of glucose present in urine, indicating indirect measurements of blood sugar. This test procedure usually calls for using a reagent strip or chemical test to detect glucose presence. This test monitors the status of abnormal blood sugar levels and manages diabetes effectively. This is one of the topics from the Excretory Products And Their Elimination chapter in Biology.

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This Story also Contains

1. Objective
2. Theory
3. Benedict's Test
4. Fehling's Test
5. Clinitest
6. Enzymatic Glucose Oxidase Test

Objective

To carry out an experiment to test for the presence of sugar in the provided urine sample.

Theory

The urine is a waste product excreted by the body, which the kidneys filter from blood. It is eliminated from the body through urination, where it comes out through the urethra. In human beings, urine is normally pale yellow and is a clear liquid consisting of water with several chemical substances added to it, including uric acid, urea, enzymes in traces, hormones, and carbohydrates.

Also Read:

• MCQ Practice on Modes of Excretion

• Excretory Products and their Elimination

• Ultrafiltration

• Human Excretory system

Characteristic of Urine

• Color: Pale yellow, caused by the pigment named urochrome.

• pH: Usually ranging from 4.6 to 8.

• Water Content: More than 95% of urine comes as water.

• Organic Substances: nitrogenous compounds like creatine, uric acid, and urea.

• More Organic Matter: lactic acid and oxalic acid.

• Inorganic Compounds: some include potassium chloride, sodium chloride, phosphates, and sulfates.

• Abnormal Constituents: Some of them include ketone bodies, glucose, proteins, bile, and blood.

• Glucose: Consistently lacking in urine. However, it may appear when blood glucose levels exceed the renal threshold (160 to 180 mg/dl). This condition, known as glucosuria, is often associated with diabetes mellitus, a metabolic disorder characterised by high blood glucose levels.

Significance of Detecting Sugar in Urine

Early Detection of Diabetes: Sugar detection in urine is very important because diabetes mellitus can lead to serious complications if the disease is not treated or kept under proper control. Some of the complications are damage to kidneys and nerves, cardiovascular diseases, and problems with vision.

Monitoring of Diabetes: For people already suffering from diabetes, checking urine sugar regularly will indeed help them manage their diseases much better by keeping medications as well as lifestyle under control.

Identification of Renal Conditions: Sugar in urine can also give a clue for renal glycosuria, an abnormality of the kidney where kidneys excrete glucose into the urine despite normal blood glucose concentration.

Tests for Detecting Sugar in Urine

The following are the tests that may be used to detect sugar in a urine sample.

• Benedict's Test

• Fehling's Test

• Clinitest

• Enzymatic Glucose Oxidase Test

What is Benedict's Test?

The test takes its name from Benedict's solution, an aqueous solution of copper(II) sulfate (CuSO4) and sodium citrate. Benedict's solution is used to test for the presence of reducing sugars.

It tests for reducing sugars of a ketose moiety in the urine of a patient. The diagnostic implications of this are that the presence of glucose in neither the human urine nor the blood is normal.

What is the Fehling Test?

Fehling's test has two solutions:

Fehling Solution A: copper(II) sulphate, blue aqua.

Fehling's Solution B: An aqueous solution that is clear, colourless, and contains sodium potassium tartrate and sodium hydroxide. When heated with the urine sample, glucose reduces the copper(II) sulfate, forming copper(II) oxide as a coloured precipitate. The colour is indicative of either the presence or the concentration of glucose in the urine.

What is Clinitest?

• The Clinitest tablet, commercially available, tests for the presence of reducing sugars in urine.

• It has in place copper sulfate, sodium hydroxide, and other reagents that if put into a sample of urine, the reaction of the glucose with those reagents, will have a similar result as Benedict's test.

• It is routinely used in clinical practice due to its ease and speed of execution.

What is the Enzymatic Glucose Oxidase Test?

• This is a test that is more specific compared to many of the others and is very much quantitative in terms of measuring glucose.

• This test uses an enzyme that is specifically reacting with glucose in its formation with the production of gluconic acid and hydrogen peroxide.

• The hydrogen peroxide reacts with a chromogen to produce a coloured compound, and the intensity of this colour can be measured spectrophotometrically, meaning that we can determine the concentration of the glucose in the urine exactly.

Benedict's Test

The detailed experiment is given below:

Apparatus Required

• Burner

• Test tube

• Sample of urine

• Test tube holder

• Benedict's solution

• Measuring cylinders

Procedure

• Take a clean, dry test tube.

• Measure using the measuring cylinder, and take 2 ml of the urine sample.

• Transfer the measured urine to the test tube.

• Add 5 ml of Benedict's reagent to the urine sample in the test tube.

• Secure the test tube with a holder and place it close to the Bunsen burner.

• Heat the test tube for 2 minutes with continuous stirring.

• Observe any changes.

Experiment And Conclusion

• A yellow precipitate after heating may appear in the test tube, and the precipitate may form slowly, indicating that there exists sugar in the urine sample.

• The sugar concentration colour determines the colour of the precipitate, where the colour may either be yellow, green, or brick red.

Fehling's Test

The detailed experiment is given below:

Requirements

• A burner

• A test tube

• Urine sample

• A test tube holder

• Measurement cylinder

• Fehling's Solution A

• Fehling's Solution B

Preparation

• Obtain a clean and dry test tube.

• Two ml of the urine sample is measured using a measuring cylinder.

• Pour the measured urine into the test tube.

• Add 2 ml of Fehling's Solution A and shake well.

• Add 2 ml of Fehling's Solution B to the same test tube and then gently shake both the solutions.

• Take the test tube with a holder and hold it by heating it near the Bunsen burner for two minutes, constantly stirring it.

• Note the changes.

Observation And Conclusion

• On heating some green precipitate is formed in the test tube indicating that sugar is present in the sample.

• The colour of the precipitate will be yellow, green, and even brick red with the sugar concentration.

Clinitest

The detailed experiment is given below:

Required materials

• Clinitest tablet

• Test tube or container

• Specimen of urine

• Water

Method

• Take a specimen of urine in a clean test tube or container.

• Add a few drops of water to the urine specimen.

• Drop a Clinitest tablet into the sample.

• Note the reaction there will be a colour change depending on the concentration of glucose.

• Match the colour produced with a standard chart provided with the Clinitest kit.

Observation And Conclusion

The colour change indicates that there are reducing sugars, like glucose, in the urine. Its intensity is proportional to the concentration of sugar.

Enzymatic Glucose Oxidase Test

The detailed experiment is given below:

Materials Needed

• Glucose oxidase reagent

• Urine sample

• Test tube

• Spectrophotometer for quantitative analysis

Procedure

• Take a sample of urine in a clean test tube.

• Add the glucose oxidase reagent to the sample.

• Let the reaction run for a specified duration.

• If you are using a spectrophotometer, then absorbance is to be measured at a max.

• Form a standard curve by comparing your results with a standard curve to give you the number of glucose in the urine.

Observation And Conclusion

• The urine sample tested turned into a coloured compound hence, glucose was present.

• The colour intensity will also give us glucose and the magnitude of glucose.

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