Hb Belleville [10(A7)AlaThr] Affects The Determination of Hb A1c by Routine Cation Exchange High Performance Liquid Chromatography

When analyzed by routine cation exchange high performance liquid chromatography (HPLC), the Hb A1c peak of a Caucasian diabetic patient from Yorkshire, UK, appeared to be an incompletely resolved doublet. One component (5.5%) eluted at the normal time for Hb A1c, whereas the other component (6.6%) eluted slightly later. The HPLC trace was otherwise normal. Analysis of the diabetic patient's blood and a tryptic digest thereof by electrospray ionization mass spectrometry (ESI-MS) identified the Hb Belleville trait. To relate Hb A1c determined by HPLC to and chain glycation determined by ESI-MS, several normal blood samples (5-14% Hb A1c) were analyzed by both techniques. The Hb A1c levels derived from the and chain glycation levels of the diabetic patient (12.9 and 12.4%, respectively) agreed with the sum of the two peaks (12.1%) in the HPLC trace. Similarly, Hb Belleville was detected and identified in another Caucasian, also from Yorkshire, with normal Hb A1c.