title: Evaluation of the short-term stability of specimens for clinical laboratory testing.
abstract: BACKGROUND
  A major concern in both the laboratory-medicine and research communities is the quality of human specimens for analysis. However, there is insufficient scientific evidence regarding optimal conditions for handling and storing routine specimens, especially those in liquid form. Thus, we investigated the stability of clinically relevant samples stored under various conditions.
  
  
  METHODS
  Ten clinical laboratories in Japan conducted analyses of the stability of post-clinical (left over after analysis) test samples in relation to temperature and storage duration. We examined serum, whole blood, and urine samples submitted to each laboratory for routine testing. In this study, at least 5 samples for each of 35 tests were analyzed at each laboratory. After completion of routine testing, specimens with sufficient residual volume and values between LL-R/2 (lower limit of reference interval) and UL+R/2 (upper limit) were divided into 300 μL aliquots, where R=UL - LL. Aliquots of serum specimens were stored at either room temperature (23°C), 4°C, -20°C, or -80°C without light exposure. Aliquots of whole blood and urine specimens were stored at either 23°C or 4°C. The storage time was either 1, 3, or 7 days. Average differences between pre- and post-storage test results were evaluated for each laboratory test by two-way ANOVA. F-values for between-day variations were used for judging the statistical significance of storage-related changes in test values, whereas the ratio of between-day SD to between-individual SD (one-fourth of reference interval) was used to indicate the practical significance of the change.
  
  
  CONCLUSIONS
  Sample denaturation is clearly temperature- and storage-duration dependent for almost all analytes. In general, specimens were most susceptible to denaturation at 23°C, then 4°C, -20°C, and -80°C. This study confirmed the accumulated routine, practice-based, detailed knowledge regarding specimen stability and will help to ensure the reliability of laboratory test results.
authors.affiliation: 1 Department of Clinical Laboratory, Kumamoto University Hospital Faculty of Health Sciences , Kumamoto, Japan .
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Ikeda
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Ichihara
authors.forename: Teruto
authors.initials: T
authors.lastname: Hashiguchi
authors.forename: Yoh
authors.initials: Y
authors.lastname: Hidaka
authors.forename: Dongchon
authors.initials: D
authors.lastname: Kang
authors.forename: Masato
authors.initials: M
authors.lastname: Maekawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Matsushita
authors.forename: Shigeo
authors.initials: S
authors.lastname: Okubo
authors.forename: Tatsuyuki
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Koh
authors.initials: K
authors.lastname: Furuta
mesh_terms: D001774:Blood Chemical Analysis; D003627:Data Interpretation, Statistical; D006801:Humans; D007564:Japan; D007753:Laboratories; D015203:Reproducibility of Results; D013048:Specimen Handling / Q000379:methods / Q000592:standards*; D013696:Temperature; D013997:Time Factors; D014021:Tissue Preservation / Q000379:methods*; D014556:Urine / Q000737:chemistry*