Albumin consists of about 60% of the total protein in the human body. It is synthesized in the liver which helps to maintain osmotic pressure in the blood. The other functions include the transportation of drugs, enzymes, and hormones throughout the body. It is also one of the important parameters for liver function test (LFT). This is generally measured based on a BCG method.
Normal range (approximate value) of albumin
- Adults:- 3.4 – 4.8 g/dl
- Newborn:- 2.8 – 4.4 g/dl
- Children:- 3.2 – 5.4 g/dl
Handling of albumin reagent
- Wear an apron and surgical gloves before carrying out the measurement.
- 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.
Working principle (BCG method)
1. Principle reaction
Albumin binds with bromcresol green (BCG) in an acid media to form an albumin-BCG complex. This complex shows a blue-green color. Thus, the intensity of albumin in the sample is determined by the intensity of this color.
2. Sample preparation
The table shown below for albumin measurement is valid for tulip, accurex, analyticon, and diasys. 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.
For making a sample test or for doing the calibration, mix the calibrator/sample with the working solution. Similarly, for making a reagent blank, replace the calibrator/sample with the same volume of distilled water (tulip, diasys). Then, mix the distilled water with the working solution. For companies such as analyticon, accurex, etc. directly feed the working solution for 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 albumin 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).