Abnormal haemoglobins, Hb Takamatsu and Hb G-Szuhu, detected during the analysis of glycated haemoglobin (HbA1C) by high performance liquid chromatography.
BACKGROUND
During medical checkups of two unrelated female outpatients during their annual health examination and one male inpatient suffering from cardiac failure the glycated haemoglobin (HbA1C) concentrations measured by high performance liquid chromatography (HPLC) were low, in spite of normal fasting plasma glucose concentrations. However, HbA1C concentrations measured by latex immunoagglutination and fructosamine concentrations were within the normal range.


METHODS
Investigations were performed to elucidate the reasons for these discrepancies.


RESULTS
Abnormal haemoglobins, Hb Takamatsu and Hb G-Szuhu, were found. The HPLC chromatogram showed an additional peak near HbA1a + b, which resulted in falsely low HbA1C concentrations. Isoelectric focusing analysis of the patients' haemoglobin disclosed abnormal haemoglobins, which migrated faster than normal HbA1 in the two female patients and slower in the male patient. The cDNA sequence and amino acid analyses of the haemoglobin alpha-chains and beta-chains indicated the presence of the haemoglobin variant beta 120 Lys-->Gln in the two female patients and beta 80 Asn-->Lys in the male patient; that is, Hb Takamatsu and Hb G-Szuhu.


CONCLUSIONS
These cases show how these silent haemoglobin variants can result in falsely low HbA1C concentration readings when using HPLC.
Moriwaki
Y
Y
Third Department of Internal Medicine, Hyogo College of Medicine, Mukogawa-cho 1-1, Nishinomiya, Hyogo 663-8501, Japan. tetsuya@hyo-med.ac.jp
Yamamoto
T
T
Shibutani
Y
Y
Harano
T
T
Takahashi
S
S
Hada
T
T
D000368:Aged; D002851:Chromatography, High Pressure Liquid; D005188:False Negative Reactions; D005260:Female; D006442:Glycated Hemoglobin / Q000032:analysis*; D006455:Hemoglobins, Abnormal / Q000032:analysis*; D006801:Humans; D007525:Isoelectric Focusing; D008875:Middle Aged
D006442:Glycated Hemoglobin; D006455:Hemoglobins, Abnormal; C047886:hemoglobin G-Szuhu; C053049:hemoglobin Takamatsu