Glycated haemoglobin A1c measurement in stored whole blood sample is reliable for clinical use

Glycated haemoglobin A1c (HbA1c) gives an integrated plasma glycaemia for the previous 2-3 months and its measurement is central in the management of diabetic patients. However in many developing countries because kits/regents or expertise for HbA1c measurement are not always available and the test must be conducted on fresh whole blood samples, HbA1c tests are not routinely performed Thus, this study aimed to determine if the degradation products from whole blood sample storage are significant enough to compromise the diagnostic value of HbA1c measurements. Two hundred and thirty-one fresh whole blood samples with pre-determined HbA1c values were stored at between 2-8 degrees C and using boronate affinity immunoassay technique, HbA1c values were then measured in the same whole blood samples after 20 days of storage. The results showed that there were no significant differences in the mean values of the initial HbA1c measurement and the values obtained after storage (7.5 +/- 2.0 vs. 7.5 +/- 2.1, p > 0.05) and this was irrespective of gender. Furthermore, irrespective of gender there were significant correlations between the HbA1c values measured in fresh whole blood samples and values obtained after storage (r = 0.83, p < 0.01). Therefore, based on these findings and other previous reports, the effect of storage degradation product was not significant enough to compromise the clinical or research use of HbA1c test results from stored whole blood samples. However, we recommend that diagnostic laboratories should evaluate their HbA1c measurement techniques for HbA1c determination in stored whole blood samples. Any persistent upward or downward bias in stored whole blood samples should be reported to guide the physician in interpreting HbA1c results from stored whole blood samples from that laboratory and/or technique.