Utilizzo di un pool di sangue umano fresco congelato per la valutazione intralaboratorio dell’imprecisione della determinazione dell’emoglobina glicata

Glycated hemoglobin (HbA 1c) has a key role for the assessment of glycemic state in diabetic subjects. To guarantee the clinical reliability of HbA 1c methods regular IQC programs are mandatory. These programs may give immediate information on the reliability of the analytical system used in the laboratory, providing that employed materials are stable and commutable. In this study we investigated two different preparations to be used as IQC material for HbA 1c, i.e. a classical lyophilized material (CQI1) and a freshly collected whole blood pool stored at -20 °C (CQI2). We also checked the stability of CQI2 at -20 °C compared to -80 °C storage. HbA 1c was determined by an immunoturbidimetric assay on Roche Cobas Integra. The mean (±SD) HbA 1c concentrations in the two materials were 9.1%±0.05 in CQI1 and 6.9%±0.05 in CQI2, respectively. In a following period of 20 weeks the HbA 1c recovery was between 94.6% and 105.7% for CQI1 and between 94.4% and 109.4% for CQI2. Most of CQI1 fluctuations were paired to similar fluctuations of CQI2, proving that these changes were independent of the material properties. When compared with results obtained at -80 °C storage, the HbA 1c concentrations in the CQI2 at -20 °C were stable over the whole study period. In conclusion, our findings demonstrate that fresh-frozen pooled whole blood stored at -20 °C is a suitable and cheap material for use in the IQC programmes for HbA 1c.