CLCS has validated the GlycoGap® (Diazyme) assay for determination of % Glycated Albumin (%GA) in patient samples. GlycoGap is a coupled enzymatic assay performed on the Roche cobas analyzer in conjunction with the bromocresol green method to measure total albumin. A previous publication by Abidin et al (1) has shown that these results correlate well with results from the Lucica® GA-L glycated albumin method.
Measurement of %GA has utility for monitoring glucose control in patients for whom hemoglobin A1c is considered unreliable. This includes those in whom the erythrocyte life span is altered, patients undergoing dialysis for end stage renal disease, or women during pregnancy. Additionally, %GA provides information on short-term (2-4 weeks) glycemic control that could be used prognostically. For references, please see (2-5).
Sample Stability and Possible Interferences
Serum is the specimen of choice. However, CLCS has also validated plasma collected in heparin-containing tubes.
Due to the presence of glucose as well as albumin in these samples, additional product continues to form after sample collection. For this reason, room temperature stability is 4 hours and stability at 2 – 8 oC is 7 days. For long-term storage, -80 oC is preferable.
Samples were found to be affected by high levels of triglycerides. Thus, the laboratory measures the lipemic index when this %GA is ordered. If levels are high enough to interfere, a footnote will be added stating: “The sample was found to contain elevated triglycerides which can cause a negative interference in our laboratory’s assay for Glycated Albumin. Results should be interpreted with caution.”
Within-run precision was determined to be <2.5 %CV for both serum and heparin plasma samples. Between-run precision was found to be <3.5% for both serum and heparin plasma samples.
Questions? Contact Jennifer Powers Carson, PhD, Laboratory Director 314-273-1378 or by email firstname.lastname@example.org.
1) Abidin D, Liu L, Dou C, Datta A, Yuan C. An improved enzymatic assay for glycated serum protein. Anal Methods 2013; 5:2461-69.
2) Freitas PAC, Ehlert LR, Camargo JL. Glycated albumin: a potential biomarker in diabetes. Arch Endocrinol Metab. 2017; 61:296-304.
3) Lu JM, Ji LN, Li YF, Li QM, Lin SS, Lv XF, et. al. Glycated albumin is superior to glycated hemoglobin for glycemic control assessment at an early stage of diabetes treatment: A multicenter, prospective study. J Diabetes Complications. 2016; 30:1609-1613.
4) Ogawa A, Hayashi A, Kishihara E, Yoshino S, Takeuchi A, Shichiri M. New indices for predicting glycaemic variability. PLoS One. 2012; 7:e46517.
5) Montagnana M, Paleari R, Danese E, Salvagno GL, Lippi G, Guidi GC, Mosca A. Evaluation of biological variation of glycated albumin (GA) and fructosamine in healthy subjects. Clin Chim Acta. 2013; 423:1-4.