Serum albumin. Differences in assay specificity.

Serum albumin is one of the most common parameters used in evaluating nutritional status. Three of the popular methods available for measuring serum albumin are serum protein electrophoresis and the two dye binding methods: BCG and BCP. BCG is currently the most popular method because of its simplicity, rapidity, and cost. Although electrophoretic methods are considered more accurate, BCP has shown to correlate well with electrophoresis in most cases. BCG often overestimates serum albumin levels, although its specificity can be improved by minimizing contact time with the serum sample. The average difference between BCG methods and other methods is usually 0.5-0.6 g/dL. From a quantitative standpoint, some might consider the difference in specificity of BCG versus the other two methods to be insignificant; however, from a qualitative standpoint, the difference could easily alter the interpretation of nutritional assessment parameters. Because of differences in analytical methods, serum albumin measurements should be interpreted in the context of the assay being used and the accepted normal range for that laboratory. Likewise, published studies, especially those that stratify degrees of malnutrition and/or risk of complications based on specific serum albumin levels, should specify the assay methodology utilized.