Immediate Elimination of Labile HbA1c With Allosteric Effectors of Hemoglobin

Abstract

Our aim was to find a simple method of removing labile glycosylated hemoglobin (HbA1c) from blood samples before it is measured by cation-exchange chromatography. Labile HbA1c is formed by the binding of glucose to the NH2-terminal valine of the beta-chain of HbA. We sought a more competitive binder for the same site to dissociate labile HbA1c to glucose and HbA. Inorganic phosphates were found to have a strong allosteric effect and a great ability to eliminate labile HbA1c. We developed our method with 4 mM tetrapolyphosphate in the hemolyzing solution to eliminate labile HbA1c during the automatic processing (at pH 6 and heated for 2 min at 45 degrees C) of blood samples for HbA1c estimation. This may be useful when estimating HbA1c by the manual method.

Insights into the Progression of Labile Hb A1cto Stable Hb A1cviaa Mechanistic Assessment of 2,3-Bisphosphoglycerate Facilitation of the Slow Nonenzymatic Glycation Process

“…In some clinical assays of stable Hb A 1c , phosphate has been added to hemolyzing solutions at levels well above physiological values (e.g. 100 mM [31]), which should therefore reduce the effective concentration of glucopyranose. This procedure will shift the equilibrium in mechanistic pathway III ( Figure 1) toward detached glucose, likely resulting in the removal of structure 3 from the Hb A 1c pocket.…”

Correlation of fasting blood glucose and haemoglobin A1c measured with an automated analyser

“…The machine tested was a Hi-Auto Alc model 8t21, which assays HbAc, HbA, and HbF in 4 min with 3 gl specimens [1]. For comparison, an older model from the same manufacturer (Hi-Auto A model 8120, which resembles the model 8110 described in [2]) was used.…”

A labile form of hemoglobin A1c is higher in African‐American youth with type 1 diabetes compared to Caucasian patients at similar glucose levels

“…This labile fraction was a nuisance as it reflected short term concentrations in glucose and its presence could confound the interpretation of HbA1c as an estimate of long‐term MBG . Taking advantage of its unstable nature, methods to remove this labile fraction such as pre‐incubating samples in low pH and/or glucose‐free buffers were introduced so as to measure the stable form of HbA1c alone . Other than its role confounding measurement of HbA1c, identifying and interpretation of labile HbA1c has been of passing clinical interest …”