Whole blood samples for adrenocorticotrophic hormone measurement can be stored at room temperature for 4 hours.

INTRODUCTION: The aim of this study was to investigate and compare the stability of adrenocorticotrophic hormone (ACTH) in whole blood stored on ice and at room temperature for up to 48 hours. This study differs from previous studies by a larger data material.

MATERIALS AND METHODS: EDTA-blood samples from 30 patients were collected, aliquoted and stored on ice or at room temperature for 0, 2, 4, 24, or 48 h before centrifugation, and the plasma was stored frozen until analysis. All samples were analyzed using an automated electrochemiluminescence immunoassay on cobas 6000 e601. The change in ACTH concentration was illustrated as ACTH recovery compared to standard conditions defined as samples stored immediately on ice, centrifuged and plasma frozen within 1 h. A change in ACTH concentration of more than 10% was considered to be of clinical relevance.

RESULTS: The results showed no clinically relevant change in ACTH recovery for up to 4 h compared to standard conditions. For samples stored at room temperature for 4 h, a significant (p < .0001) relative mean change in ACTH concentrations of -4.3% was observed.

CONCLUSION: The comparison between samples stored at room temperature for up to 4 h and standard conditions showed that ACTH samples do not require cooling until centrifugation, if a mean difference in ACTH concentration of -4.3%, between the individual results, can be accepted.