Estabilidad de analitos conservados en tubo cerrado con film versus cerrado con tapa plástica

Introduction

The laboratory must be able to guarantee the stability of stored patient samples for confirmation of results or errors in the interpretation of the medical request. The aim of this study was to evaluate the stability of the blood analytes preserved in tubes sealed with film versus a plastic cap.

Material and methods

A total of 24 blood samples were aliquoted into two tubes; one sealed with film, and the other with a plastic cap. Twenty-six clinical chemistry analytes were measured for 7 consecutive days using a Roche Cobas c 501 autoanalyser. The samples were stored in a refrigerator between 2-8 C. The total error and coefficient of variation were calculated, and the results were compared against the quality requirements of the laboratory.

Conclusions

The variation was higher in the tubes sealed with film than in those with a plastic cap. Enzymes remained within the quality requirements for four days, and ions, apart from iron, were stable for only one day. The metabolites were stable for seven days excluding glucose, uric acid, total proteins, and albumin. It is suggested that each laboratory must evaluate the stability of analytes based on its workflow.