Estabilidad de analitos conservados en tubo cerrado con film versus cerrado con tapa plástica / Stability of analytes stored in a tube sealed with film versus closed with plastic cap

RESUMEN

Introducción: El laboratorio debe garantizar la estabilidad de las muestras conservadas con la finalidad de una eventual confirmación de resultados o corregir posibles errores u omisiones al ingresar las solicitudes médicas. Con este objetivo se comparó la estabilidad de los analitos de muestras conservadas en el tubo primario selladas con film contra cierre con tapa plástica. Material y métodos: Veinticuatro muestras de sangre fueron alicuotadas en dos tubos primarios, uno cerrado con tapa plástica y otro con film. A ambas alícuotas se les midieron 26 analitos de química clínica durante siete días consecutivos, en un autoanalizador Cobas c 501 de Roche y se conservaron en refrigerador a 2-8°C. Se calcularon los coeficientes de variación y el error total. Los resultados obtenidos se compararon con el requisito de calidad respectivo establecido por el laboratorio. Conclusiones: Se observó una mayor variabilidad en los tubos cerrados con film respecto de los cerrados con tapa plástica. Todas las enzimas evaluadas cumplieron el requisito de calidad durante 4 días. A excepción del hierro todos los iones fueron estables solo un día. Los metabolitos fueron estables durante una semana a excepción de glucosa, proteínas totales, ácido úrico y albúmina. Se recomienda que cada laboratorio evalúe la estabilidad de los analitos en base a su forma de trabajo

ABSTRACT

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 2-8C. 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