Test for the Presence of Albumin in the Urine

Albumin Protein: An Introduction

Albumin is a protein produced by the liver. This is mainly found in the blood and helps to keep fluid from leaking out of our blood vessels into other tissues. Albumin also carries hormones, vitamins, and enzymes in the blood. Without enough albumin, fluid can leak out of our blood and build up in our lungs, abdomen, or other body parts.

A trace amount of albumin is found in normal urine daily. The normal amount of albumin in the urine is less than 250 mg (in 24 hours urine sample).

Under pathological conditions, like Albuminuria, the albumin found in urine will be way above the normal level.

Table of Content

• Aim

• Theory

• Material Required

• Procedure

• Observation

• Result

• Precaution

Aim

To experimentally test the presence of albumin in the urine.

Material Required

• Urine sample

• test tube

• test tube holder

• 33% acetic acid

• Bunsen burner

• Dropper

Theory

The basic principle behind the heat coagulation test is the change in the protein’s structure because of high temperature and the change in pH. Heating a protein in an acidic condition causes the denaturation of proteins. Denaturation involves breaking weak hydrogen bonds responsible for proteins' secondary, tertiary, and quaternary structures; they become uncoiled and adhere to each other and form an insoluble mass.

In the test of heat coagulation of albumin. Heating cause denaturation of secondary, tertiary, and quaternary structure, only the primary structure remains intact, and the acetic acid added aids the breaking of the peptide bonds in the protein molecules, which facilitates the process of coagulation and adjust the pH at the isoelectric point of albumin which is 4.7.

Procedure

Step 1. Take a test tube, and hold it with a test tube holder.

Step 2. Fill two-thirds of the test tube with the urine sample.

Step 3. Incline the test tube at an angle and heat the upper one-third part of the tube in a low flame on a Bunsen burner.

Step 4. White cloudy precipitate develops in the heated one-third part of the urine sample.

Step 5. Add 1% acetic acid drop by drop, or simply add a drop of 33% acetic acid and boil.

Step 6. Wait and observe the appearance of the urine sample.

Test for the presence of albumin in the urine

Observation

After adding acetic acid and again boiling, if the turbidity appears and intensifies or remains, it indicates the presence of albumin in the urine.

Result

The positive outcome of heat coagulation is observed by the appearance of a turbid white precipitate on the top of the mixture. The lower portion of the solution acts as a control and compares the cloudiness that appears in the upper part.

Precautions

• Clean the test tube before and after experimenting.

• Handle the chemicals carefully.

• Add acetic acid carefully, as the excess of acetic acid may dissolve traces of protein, giving a negative result.

Limitations

• In certain situations, it could yield a positive result for other proteins

• It is crucial to ensure the pH is within the range of the isoelectric pH of albumin.

Lab Manual Questions

1. What are the colour of the urine and the pigment responsible for this characteristic?

Ans: the normal colour of urine ranges from pale yellow to deep yellow colour. Urochrome pigment is responsible for this characteristic colour.

2. In which organ of our body highly toxic ammonia is converted into urea?

Ans: In the liver, ammonia is converted to a non-toxic compound called urea, which is then transported through the blood to the kidney.

3. Name the disorder in which glucose level is high in the urine.

Ans: Glucosuria is a condition in which there is a high level of glucose in urine.

4. Which reagent will demonstrate the presence of protein in urine?

Ans: Adding sulphosalicylic acid to the urine sample creates whitish-cloudy turbidity (coagulation) in the solution, indicating protein in the urine sample. 

Viva Questions

1. What is the normal range of protein in urine?

Ans: normal range of protein in urine is less than 250 mg/ 24 hours sample.

2. What type of sample is preferred for urine protein tests?

Ans: early morning sample is preferred for testing the protein in the urine.

3. What are the different types of proteins found in urine?

Ans:

• Albumin

• Globulin

• Mucin

• Haemoglobins

4. What is the advantage of the heat coagulation test?

Ans: cheap test which does not require technical expertise.

5. What is the disadvantage of the heat coagulation test?

Ans: A specific type of protein cannot be specified.

6. Why should the test tube only heat on the upper one-third part?

Ans: urine in the lower portion of the test tube acts as a control and is to compare the cloudiness developed in the upper part of the test tube.

7. What is albuminuria?

Ans: albuminuria is a sign of kidney dysfunction. The level of albumin in the urine is much higher than the normal range.

8. What is the cause of albuminuria?

Ans: a damaged kidney lets some albumin pass into urine.

9. How to reduce albumin in urine?

Ans: to reduce albumin in urine, one can take medicines that lower the blood pressure prescribed by the physician.

10. What does acetic acid do in the heat coagulation test?

Ans: acetic acid added aids the breaking of the peptide bonds in the protein molecules, which facilitates the coagulation process and adjusts the pH at the isoelectric point of albumin, which is 4.7.

Practical Based Questions

1. What are the building blocks of protein?

1. DNA

2. RNA

3. Nucleotides

4. Amino acids

Ans: D)  amino acids

2. What is a polypeptide having a molecular mass greater than 10,000 called?

1. Amino acids

2. Fats

3. Dipeptides

4. Proteins

Ans: D) proteins

3. Which of the proteins does not coagulate on heating?

1. Albumin

2. globulin

3. histone

4. mucoproteins

Ans: D) mucoproteins

4. Which of the following statements is valid for the primary structure of proteins?

1. The sequence of amino acids joined by weak hydrogen bonds

2. subunit of protein

3. a peptide bond joins amino acid sequences

4. form the helical structure of the protein

Ans: C) a peptide bond joins amino acid sequences

5. which protein structures are broken during the denaturation of protein

1. secondary structure

2. tertiary structure

3. primary structure

4. both a and b

Ans: D) both a and b

6. The isoelectric point of albumin?

1. 5.6

2. 4.7

3. 2.6

4. 9.4

Ans: B) 4.7

7. What causes a high level of albumin in the urine

1. Low blood pressure

2. Kidney dysfunction

3. High blood pressure

4. Both b and c

Ans: D) both b and c

8. If turbidity disappears in the heat coagulation experiment of urine, this indicates

1. Presence of fat

2. Presence of phosphate and carbonate

3. Presence of globulin protein

4. None of the above

Ans: D) presence of phosphate and carbonate

9. How to reduce albumin in urine?

1. Regular exercise

2. Medication

3. Proper diet

4. All of the above

Ans: D) all of the above

10. What is the bond of amino acids called?

1. Ionic bond

2. Covalent bond

3. Peptide bond

4. Hydrogen bond

Ans: C) peptide bond

Summary

A whitish cloudy turbid precipitate (coagulation) in the solution indicates the presence of albumin in the urine sample. A trace of albumin, which is less than 250 mg (in 24 hours urine sample), is found in normal urine. In kidney dysfunctions like albuminuria, albumin is found in urine above normal level.