RT Journal Article
SR Electronic
T1 Application of smoothed continuous labile haemoglobin A1c reference intervals for identification of potentially spurious HbA1c results
JF Journal of Clinical Pathology
JO J Clin Pathol
FD BMJ Publishing Group Ltd and Association of Clinical Pathologists
SP 712
OP 716
DO 10.1136/jclinpath-2014-202346
VO 67
IS 8
A1 Loh, Tze Ping
A1 Peng, Weng Kung
A1 Chen, Lan
A1 Sethi, Sunil Kumar
YR 2014
UL http://jcp.bmj.com/content/67/8/712.abstract
AB Aims We aim to develop smoothed continuous 2.5th and 97.5th percentile values for labile glycated haemoglobin A1c to glycated haemoglobin A1c (LHbA1c:HbA1c) ratio against HbA1c, and apply them on our patient population for identification of potentially spurious HbA1c measurements. Methods The LHbA1c and HbA1c were measured using Bio-rad Variant II high-performance liquid chromatography system. We recorded the LHbA1c and HbA1c values of 1555 patients who had normal chromatograms. Using these results, the 2.5th and 97.5th percentile reference limits of the LHbA1c:HbA1c ratio were described by LHbA1c:HbA1c=−0.0072×HbA1c +0.2925 and LHbA1c:HbA1c=−0.0132×HbA1c +0.5327, respectively. Results When the reference intervals were applied on a separate 1000 patients, 34 and 29 of them had abnormally high and low LHbA1c:HbA1c ratios, respectively. Most of the observed high ratios were associated concurrently with elevated plasma glucose, anaemia, chronic liver and kidney diseases. A suppressed ratio was mostly associated with haemoglobin variants. Patients with heterozygous HbE or HbS variants tend to have lower LHbA1c:HbA1c ratios while the converse is true for heterozygous HbJ. Conclusions The continuous LHbA1c:HbA1c ratio may be used to detect confounding factors or spurious HbA1c results, but its performance is confounded and reduced by the ambient plasma glucose.