Background: Storage of biological samples may alter the values of an analyte compared to that of initial measurement. Therefore, an optimal storage condition for every analyte in serum and whole blood samples needs to be determined. The aim of this study was to investigate stability of 34 analytes at different time and temperature conditions of storage.
Methods: This study assessed the stability of hematological parameters in whole blood sample and common biochemical analytes in serum of 40 diabetic patients after 24 and 48 hours in 2 - 8°C and after 30 days in -20°C of sample collection. The mean values of analytes in 3 different storage conditions were measured and compared to that of initial values.
Results: Most of the examined biochemical analytes and hematological parameters were stable up to 48 hours at 2 - 8°C after sample collection. Most of the negative changes were negligible but PTH level dramatically decreased after 48 hours in 2 - 8°C. In addition, although a clear increase in the concentration of triglycerides, Cr, Urea, T4, and 25-OH vitamin D3 was observed, it was not significant. Furthermore, a statistically significant difference was observed in the values of ALT, Ca, and T4 among the different conditions of storage. Also, values of HbA1c did not show any significant statistical changes among the 3 different conditions of storage.
Conclusions: Taken together, it seems that most of the analytes in the serum of diabetic patients as well as HbA1c are stable up to 30 days of storage.