Colorimetric versus radioimmunological measurement of glycated and non-glycated serum albumin after affinity chromatography

Abstract

Affinity chromatography by m-aminophenylboronic acid has been proposed for routine measurement of glycated albumin. We assayed glycated and non-glycated fractions of serum albumin (HSA) eluted by affinity chromatography columns by both a specific RIA method for the human serum albumin (HSA) and by a colorimetric method. Sixteen diabetic patients presented a significantly higher percentage of glycated-HSA than 7 control subjects with both methods, and a strong correlation was found between the values obtained with the two methods. RIA was able to detect a significant concentration of glycated-HSA in all normal subjects, while the colorimetric method was not. The accuracy of separation between the glycated and non-glycated fractions of albumin was tested using [14C]glucose as tracer. When [14C]glycated-HSA purified by Sephadex G25 filtration was chromatographed using the m-aminophenylboronic acid, only 5.3% of the total 14C-radioactivity present in the solution was recovered in the bound fraction, while 44.0% was eluted in non-protein-bound fraction and 54.7% was retained in the column. Our findings confirm that affinity chromatography by m-aminophenylboronic acid can be a useful tool in the monitoring of short glycemic control of diabetic patients. Our data also indicate that the affinity chromatography with m-aminophenylboronic acid does not accurately discriminate between glycated and non-glycated fraction of HSA.