Japanese standard reference material JDS Lot 2 for haemoglobin A1c. II: Present state of standardization of haemoglobin A1c in Japan using the new reference material in routine clinical assays.
BACKGROUND
In 2001, the Committee on Standardization of Laboratory Testing Related to Diabetes Mellitus of the Japan Diabetes Society (JDS) prepared and certified a new reference material for haemoglobin A1c (HbA1c), Lot 2. The standardization programme for HbA1c measurement in Japan is currently based on Lot 2, although some laboratories still use the previous material (Lot 1). The values assigned to Lot 2 were based on the consensus values for Lot 1 and should give the same results. Therefore, there should be no difference in the measured values no matter which calibrators are used. The Committee conducted a domestic survey in order to confirm this relationship.


METHODS
In November 2002, four samples for HbA1c assay were sent to 795 laboratories as part of a national survey in Japan. Assays were performed using the laboratories' routine clinical methods. The coefficients of variation (CVs) of the reported values from all laboratories for the samples were calculated in order to determine the current level of standardization in Japan.


RESULTS
The overall CVs in the measured values for the four samples ranged from 2.7% to 4.0%. Values from laboratories using calibrators based on Lots 1 and 2 were similar.


CONCLUSIONS
The present state of standardization for the routine measurement of HbA1c in Japan, as indicated by the 2002 survey, is excellent. This should aid in the eventual conversion of Lot 2 to IFCC-based values from the results of the 2002 national HbA1c survey.
Tominaga
Makoto
M
Department of Laboratory Medicine, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan. mtominag@med.id.yamagata-u.ac.jp
Makino
Hideichi
H
Yoshino
Gen
G
Kuwa
Katsuhiko
K
Takei
Izumi
I
Aono
Yukuko
Y
Hoshino
Tadao
T
Umemoto
Masao
M
Shimatsu
Akira
A
Sanke
Tokio
T
Kuwashima
Masamichi
M
Taminato
Tomohiko
T
Ono
Junko
J
D001774:Blood Chemical Analysis / Q000379:methods / Q000592:standards*; D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D003920:Diabetes Mellitus / Q000175:diagnosis*; D006442:Glycated Hemoglobin / Q000032:analysis* / Q000592:standards; D006801:Humans; D007118:Immunoassay; D007564:Japan; D007753:Laboratories / Q000592:standards*; D011786:Quality Control; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D006442:Glycated Hemoglobin