Diabetes Care, Vol 23, Issue 3 339-344, Copyright © 2000 by American Diabetes Association
Evaluation of HbA1c determination methods in patients with hemoglobinopathies
WJ Schnedl, R Krause, G Halwachs-Baumann, M Trinker, RW Lipp and GJ Krejs
Department of Internal Medicine, Karl-Franzens University, Graz, Austria. wolfgang.schnedl@kfunigraz.ac.at
OBJECTIVE: To evaluate commercially available determination methods for
HbA1c in patients with hemoglobin variants. RESEARCH DESIGN AND METHODS:
HbA1c values were determined with various commercially available methods,
including ion-exchange high-performance liquid chromatography (HPLC),
boronate affinity assay, and immunoagglutination in patients with the
hemoglobin mutations Hb Graz, Hb Sherwood Forest, Hb O Padova, Hb D, and Hb
S. RESULTS: The effect of hemoglobinopathies on glycohemoglobin
measurements was highly method dependent. The HPLC methods for HbA1c
determination lacked the resolution necessary to differentiate hemoglobin
variants. They demonstrated additional peaks in the chromatograms and HbA1c
results either too low or too high compared with the nondiabetic reference
range. With all immunoassays, Hb Graz demonstrated falsely low values. The
other hemoglobinopathies in our study caused falsely low and/or high HbA1c
results in immunoagglutination methods. The boronate affinity method showed
values in an acceptable range for all hemoglobin variants. CONCLUSIONS:
Because of the local occurrence of Hb variants and the ethnic origin of a
given population, every individual laboratory must establish and validate
its own assay method. In managing diabetic patients, knowledge of
hemoglobinopathies influencing HbA1c determination methods is essential
because hemoglobin variants could cause mismanagement of diabetes resulting
from false HbA1c determinations.