24-42 month stability of internal blood standards for glycated hemoglobin analysis

The stability of fresh and out-of-date Blood Bank standards for quality control of glycated hemoglobin testing was extensively documented. Eight blood standards were prepared as aliquots of washed erythrocytes, stored at -70 degrees C, and assayed in duplicate repeatedly for 24 to 42 months. Significant differences over time were noted only occasionally, and exhibited no consistent trend. Ambient room temperature, 'season of the year', and various mini-column lot numbers had no consistent effect on any blood standard values. In conclusion, washed erythrocytes from controls and patients with IDDM can be stored for future analysis for at least 24 months at -70 degrees C. Out-of-date blood from the Blood Bank can be used with equal stability for at least 18 months.