Serum or Plasma Substance Concentration (Bromocresol Green Dye Binding)

What This Test Measures

Bromocresol green (BCG) is a dye that binds to certain proteins in your blood, particularly albumin. When mixed with your serum or plasma, the dye’s ability to bind is measured, which can reflect overall protein levels or functional integrity. This method is less common today but historically used to assess albumin or other protein-binding capacity.

Why It Might Be Ordered

Doctors may order this test to investigate conditions affecting protein metabolism, such as liver disease, kidney problems, or nutritional deficiencies. It can also be part of broader evaluations for protein-related disorders, though newer tests are often preferred for specificity.

Sample Collection and Preparation

A blood sample is drawn from a vein, typically in the arm. The blood is then separated into serum (liquid after clotting) or plasma (liquid before clotting) for testing. This test requires a fresh sample, as dye binding can change over time.

Clinical Significance

While less frequently used today, results from this test can indirectly suggest issues with protein synthesis or breakdown. For example, low binding may indicate liver dysfunction or malnutrition. However, interpretation often requires clinical correlation with other tests or symptoms.