Glycosylated haemoglobin and plasma glycoprotein assays by affinity chromatography.

A rapid chromatography method for separating glycosylated protein from non-glycosylated protein, using a boronate-agarose affinity medium which selectively binds the cis-diol groups of glycoproteins, was used to quantitate plasma glycoprotein as well as glycohaemoglobin. The results were found to be independent of: (1) temperature from 16.5 to 29.8 degrees C; (2) haemoglobin variants, and (3) aldimine glycoprotein adducts. Thus several of the common problems occurring in existing haemoglobin A1 assays are eliminated. There was a close correlation between glycohaemoglobin measured by affinity chromatography and haemoglobin A1 by cation-exchange (r = 0.959, n = 215). Specimens from 103 diabetic patients and 112 healthy volunteers were assayed. The following reference ranges were established: glycohaemoglobin 5.5-8.4%; glycosylated total protein 11.5-16.2%; glycoalbumin 11.6-19.5%.