How is Total Protein Calculated?
Total protein in blood is calculated by directly measuring albumin and then deriving the globulin level. This is because total protein is comprised of albumin and globulin.
A blood test will directly measure the amount of albumin, a major protein in your blood. Globulin levels are then calculated by subtracting the albumin level from the total protein level. The formula is:
Globulin = Total Protein - Albumin
This indirect calculation of globulin is often utilized alongside the direct measurement of total protein and albumin. The ratio of albumin to globulin (A/G ratio) can then also be determined.
Methods for Measuring Total Protein
Several methods exist for measuring total protein, including:
- Biuret Method: This is a colorimetric assay that measures peptide bonds.
- Kjeldahl Method: This method determines the nitrogen content, which is then used to calculate the protein level. It's a more classical method that is considered a gold standard.
- Bicinchoninic Acid (BCA) Assay: Another colorimetric assay, frequently used as it is compatible with many detergents.
- Bradford Assay: A dye-binding assay, this is widely used due to its simplicity. However, it's important to note that it may show variability with different protein types.
- Dumas Method: This method uses combustion to measure the total nitrogen content. It is known for its accuracy and speed.
Different laboratories might use various methods for measuring total protein; however, the principle of calculating globulin from total protein and albumin remains consistent.
These methods are used in clinical settings to assess various health conditions. Total protein levels alone don't provide a complete picture but serve as an indicator in conjunction with other tests.
