Research on the stability changes in expert consensus of the ACTH detection preprocessing scheme

Abstract

Objectives Adrenocorticotropic hormone (ACTH) is extremely unstable and can easily degrade at room temperature. The experts agreed that the samples should be transported in an ice bath. If it cannot be detected immediately, the plasma should be separated and frozen, which is difficult to carry out in routine practice. This study was performed to explore the preanalytical factors that influence the stability of adrenocorticotrophic hormone (ACTH) measurements. Methods ACTH levels in 21 EDTA whole-blood samples were measured immediately after 0 h and then divided into three equal groups according to the corresponding values (low, L; median, M; and high, H). Next, three sample processing methods (including seven subtypes) were used: whole blood was uncentrifuged (named the A method), stored at 4 °C or 22 °C, centrifuged but not subjected to plasma removal (the B method), stored at 4 °C or 22 °C, and centrifuged with the plasma removed and stored (the C method) at 4 °C, 22 °C, and −20 °C. Each subtype contained three samples, namely, L, M, and H; these samples were retested using a Siemens XP2000 at different times. The change bias was calculated at 0 h. Results Compared to that at 0 h, there was no significant change in ACTH up to 24 h when the sample was stored at 4 °C or 22 °C with the B method (p>0.05), while it significantly changed (up or down >10 %) at 4 °C/24 h (bias is expressed as the mean±SEM; 13.37±21 %, p<0.05) and 22 °C/12 h (9.13±7.68 %, p<0.05) with the A method; and 4 °C/24 h (8.93±5.54 %, p<0.05), 22 °C/12 h (9.5±4.47 %, p<0.05) and −20 °C/3 h (12.03±4.8 %, p<0.05) with the C method. Conclusions After ACTH samples were centrifuged, the presence of plasma without removal did not affect the detection value, and the sample was stored at 4 °C for up to 24 h. There was a significant difference in the detection of ATCH when the sample was stored at −20 °C and thawed again (p<0.05).