An evaluation of the overestimation of serum albumin by bromcresol green.

Repeated observations have shown that the bromcresol green method overestimates serum albumin. Random patient serum samples were analyzed by a bromcresol green method using the Technicon AutoAnalyzer and by serum protein electrophoresis using cellulose acetate. The mean AutoAnalyzer value was 4.29 g/dl and the mean protein electrophoresis value was 3.68 g/dl (r = 0.915, slope = 0.869, y intercept = 1.090 g/dl where bromcresol green is on the Y axis, n = 166). Studies of the interference of proteins other than albumin in the bromcresol green method using the Technicon AutoAnalyzer showed that alpha globulins produce approximately a third, beta globulins a ninth, fibrinogen a fifth and hemoglobin equal the color intensity with the bromcresol green reagent that a comparable weight of albumin produced. In the bromcresol green method using the Du Pont ACA the interferences were even greater. At present, serum protein electrophresis is the most reliable method generally available to measure serum albumin. A modified bromcresol green method or immunoassay may eventually prove to be the method of choice.