Impact of delayed centrifugation on the stability of 32 biochemical analytes in blood samples collected in serum gel tubes and stored at room temperature.

Objectives: Evaluate the stability of 32 biochemical analytes in venous blood samples stored at 18-25 °C under different time delays prior to centrifugation.

Methods: A prospective study was conducted involving 33 healthy volunteers. Four venous blood samples were collected from each participant. One sample was designated as baseline and processed immediately according to the tube manufacturer's guidelines for centrifugation and analysis. The remaining three samples were stored under predefined conditions and centrifuged at different time intervals before undergoing analysis.

Results: Acceptable stability over the maximum storage time of 8 h was observed for 25 of the analytes tested in this study. However, direct bilirubin became unstable at 6 h and triglycerides at 8 h of storage prior to centrifugation. Calcium, gamma-glutamyl transferase, glucose, inorganic phosphate and potassium were found to be unstable in serum after 4 h of delayed centrifugation.

Conclusions: A delay in centrifugation of samples affected the stability of several analytes evaluated in the study, resulting in changes in their concentration or integrity. The analytical results for these analytes cannot be considered reliable as they do not meet the standards required for clinical validation. This underscores the importance of following stringent pre-analytical protocols to maintain the accuracy and reliability of laboratory diagnostic results.