Preanalytical Stability of Adrenocorticotropic Hormone Depends on Time to Centrifugation

전혈에서 시간과 온도에 따른 Adrenocorticotropic Hormone의 안정성 평가

  • Shin, Sun-Young (Department of Nuclear Medicine, Seoul National University Boramae Hospital) ;
  • Lee, Hyun-Joo (Department of Nuclear Medicine, Seoul National University Boramae Hospital) ;
  • Min, Gyung-Sun (Department of Nuclear Medicine, Seoul National University Boramae Hospital) ;
  • Lee, Ho-Young (Department of Nuclear Medicine, Seoul National University Boramae Hospital)
  • 신선영 (서울특별시보라매병원 핵의학과) ;
  • 이현주 (서울특별시보라매병원 핵의학과) ;
  • 민경선 (서울특별시보라매병원 핵의학과) ;
  • 이호영 (서울특별시보라매병원 핵의학과)
  • Received : 2009.03.11
  • Accepted : 2009.04.02
  • Published : 2009.05.11

Abstract

Background: Preanalytical factors can affect reliability of hormone assay results. Adrenocorticotropic hormone (ACTH) in blood is considered highly unstable because of proteolytic degradation, so storage of blood samples on ice until analysis is recommended. In clinical practice, however, this procedure may present logistical problems because most samples for ACTH measurement must be shipped from the place of sample collection to the laboratory. Therefore, we studied the impact of time and temperature before plasma separation and analysis on the results of ACTH assays. Methods: A total number of 22 patients were enrolled in this study. We obtained 2 blood samples. ACTH concentrations were 35~126 pg/mL. ACTH concentrations were measured by immunoradiometric assay (IRMA) using commercial kits (CIS Biointernational, Gif-sur-Yvette, France). Results: ACTH levels showed a significant difference between the samples of $22^{\circ}C$ EDTA and $4^{\circ}C$ EDTA. Measured ACTH concentrations significantly decreased with time before freezing at $-20^{\circ}C$. ACTH levels showed no significant difference between the groups of after storage for 24 hr without centrifugation at $22^{\circ}C$ and $4^{\circ}C$. Conclusion: We recommend that blood samples be obtained on pre-chilled EDTA collection tubes. The shortest possible time between sample collection and processing is always the best laboratory practice.