Total Protein- A/G Ratio, Biuret Method of Measurement

Total protein means the summation of two types of proteins found in our body. One of them is albumin while the other one is globulin. Hence, the albumin to globulin ratio (A/G ratio) indicates the composition of these two factors in the total protein. Both of them are present in the blood (serum). The total protein is mainly produced in the liver, plasma cells, lymph nodes, spleen, and bone marrow. It is also present in enzymes and hormones.  The concentration of total protein in the blood sample is measurable by the biuret method. Here, we will discuss the A/G ratio, the Biuret method of measurement of the total protein in a semi-auto biochemistry analyzer, and the contact detail of the authorized dealers for the purchase of the reagent of Spinreact Company in Kathmandu, Nepal.

Total Protein Normal Range

The value shown below is the level of total protein found in the bloodstream (serum). However, this is an approximate value. This value can slightly vary from one laboratory to another, based on the method of testing, the type of reagent used, etc. It can also differ due to geographical variation, habitat, age, sex, etc.

  • Children:- 5.6 – 8 g/dl
  • Adults:- 6.4 – 8.3 g/dl

An increased level of total protein can be the cause of dehydration, chronic inflammation, bone marrow disorder, etc.  Similarly, the decreased level can be found in the cases of liver or kidney-related diseases,  malnutrition, hemorrhage, etc. So, if the level of total protein is out of range he/she is recommended to visit the doctor.

Estimation of Total Protein by Biuret Method

1. Principle Reaction

Cupric ions react in an alkaline solution with the total protein, present in the biuret reagent to form blue colored biuret complex. The intensity of the formed color is directly proportional to the concentration of protein present in the serum.

2. Sample Preparation

The table shown below for total protein measurement is valid for the reagents of Tulip, Accurex, Analyticon, and Diasys Companies. So, if you have the reagent kit of any other company, then there can be minor fluctuation in the method.

If you have two reagents, then make a working solution out of them. The ratio of their composition will be given in the literature of your reagent kit or the reagent bottle. Else, a single reagent can also be found based on the company. In that case, that single reagent kit will act as a working solution for you.

If you need to do any external incubation, then you can use an incubator or dry bath. For a reagent blank (Analyticon, Accurex, etc.), you can directly feed the working solution in a semi-auto biochemistry analyzer. In the case of Diasys or Tulip, you need to mix the working solution with the distilled water (equal to the sample volume used in making a sample test) for making a reagent blank.

Always remember that sipping volume < sample volume + reagent volume. So that means, make sufficient sample volume to feed into the semi-auto biochemistry analyzer. Else, it will suck up the air and will give the fault reading.

If the concentration of total protein is too high (out of range/ non-linear), then dilute the sample with 0.9% NaCl or distilled water at the ratio of 1:y. Finally, when you get the result, multiply the value with the dilution factor (1+y).

3. Programming of Total Protein for a Semi-Auto Biochemistry Analyzer (Biuret Method)

Total protein, Biuret Method
Biuret Method

4. Handling of the Total Protein Reagents

You need to be extra careful while handling the reagents. So here are few tips that you are suggested to follow.

  • Wear an apron and surgical gloves before carrying out the measurement. Else the reagents may spoil your clothes. Hence the dress may get damaged.
  • Look for the expiry date of the reagents during purchase and measurement time. Suppliers tend to give you reagent kits with a low expiry interval.
  • Once you open the reagent bottles, the lifespan will decrease. So, look in your reagent kit literature for that.
  • Bring the reagents and samples to room temperature before you can carry out any measurement.
  • Always store reagents in the refrigerator when not in use.

5. Supplier of Total Protein Reagent

There are many suppliers which deal with the reagent of many companies. Some of the reagents found in the market are that of Accurex, Tulip, Erba, Human, Diasys, Analyticon, etc. Among all of these, one of the authorized dealers in Kathmandu is Mandawi Enterprises Pvt. Ltd. It deals with the reagent of Spinreact company. The supplier is located in Thapathali, Kathmandu. If you are interested to purchase the reagent of Spinreact company, then you can contact the given number (+977 9849034738).

Albumin/Globulin Ratio (A/G Ratio)

As the name suggests, the A/G ratio is the ratio of albumin with respect to globulin. The normal level of the A/G ratio ranges from 1.2:1 to 1.5: 1. But in the case of abnormalities, this ratio can alter. An increase in the ratio can either refer to an increase in the albumin level or a decrease in the globulin level. Similarly, a low A/G ratio can either indicate, a low level of albumin or a high level of globulin.



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