Evaluation of biological variation of glycated albumin (GA) and fructosamine in healthy subjects.

ABSTRACT

BACKGROUND: Glycated albumin (GA) and fructosamine are nonenzymatically glycated proteins still frequently utilized for monitoring glycemic control in diabetics. To investigate the analytical variation and the degree of individuality of these glycemic markers, we have performed an experimental study under a well designed and standardized protocol. METHODS: We collected five specimens from each of 18 apparently healthy subjects (9 men and 9 women, ages 26-52 years), on the same day, every two weeks for two months. Samples were stored at -80°C until analysis and assayed in duplicate in a single analytical run. GA and fructosamine were measured using enzymatic (Lucica®GA-L, Asahi Kasei Pharma, AKP, Tokyo, Japan) and colorimetric assays, respectively, on a Modular P Roche system (Roche Diagnostics GmbH, Mannheim, Germany). Data were analyzed by ANOVA. RESULTS: Analytical coefficient of variation (CVA) was 1.7%, 2.3% and 2.8% for GA, albumin and fructosamine, respectively. Within-subject (CVW) and between-subject (CVG) coefficients of variation were 2.1% and 10.6% for GA, 2.3% and 2.9% for albumin, and 2.3% and 6.3% for fructosamine. The estimated critical difference (CD) was 7.5% for GA, 9% for albumin and 10% for fructosamine. CONCLUSIONS: The good quality achieved by the analytical method for GA assessment and the reduced within-subject biological variation would allow to recommend this test in clinical practice for evaluation of glycemic control along with measurement of glycated hemoglobin.