The effects of a freeze-thaw cycle and pre-analytical storage temperature on the stability of insulin-like growth factor-I and pro-collagen type III N-terminal propeptide concentrations : implications for the detection of growth hormone misuse in athletes
Deutscher übersetzter Titel: | Die Auswirkungen eines Einfrier-/Abtauzyklus und der voranalytischen Lagerungstemperatur auf die Stabilität des insulinartigen Wachstumsfaktors I und die Konzentrationen von Pro-Kollagen Typ III N-terminalen Propeptiden : Implikationen für den Nachweis eines Missbrauchs von Wachstumshormonen bei Sportlern |
---|---|
Autor: | Guha, Nishan; Erotokritou-Mulligan, Ioulietta; Bartlett, Christiaan; Cowan, David A.; Bassett, E. Eryl; Stow, Michael; Sönksen, Peter H.; Holt, Richard I.G. |
Erschienen in: | Drug testing and analysis |
Veröffentlicht: | 4 (2012), 6, S. 455-459, Lit. |
Format: | Literatur (SPOLIT) |
Publikationstyp: | Zeitschriftenartikel |
Medienart: | Gedruckte Ressource Elektronische Ressource (online) |
Sprache: | Englisch |
ISSN: | 1942-7603, 1942-7611 |
DOI: | 10.1002/dta.1339 |
Schlagworte: | |
Online Zugang: | |
Erfassungsnummer: | PU201208005721 |
Quelle: | BISp |
Abstract
A method based on two serum biomarkers – insulin-like growth factor-I (IGF-I) and pro-collagen type III N-terminal propeptide (P-III-NP) – has been devised to detect growth hormone (GH) misuse. The aims of this study were to determine the stability of IGF-I and P-III-NP concentrations in serum stored at −20°C and to establish the effects of one freeze-thaw cycle. Blood was collected from 20 healthy volunteers. Serum aliquots were analyzed after storage for one day at 4°C and one day, one week, five weeks, and three months at −20°C. IGF-I and P-III-NP results were combined to calculate a GH-2000 discriminant function score for each volunteer. Inter-assay precision was determined by analysing one quality control sample at each time-point. A single freeze-thaw cycle, storage of serum at 4°C for one day and at −20°C for up to three months had no significant effect on IGF-I or P-III-NP concentration. Intra-sample variability for IGF-I was 6.8% (Immunotech assay) and 12.9% (DSL assay). Intra-sample variability for P-III-NP was 10.9% (Cisbio assay) and 13.7% (Orion assay). When IGF-I and P-III-NP results were combined, intra-sample variability of the GH-2000 score expressed as a standard deviation varied between 0.31 and 0.50 depending on the assay combination used. Variability in IGF-I and P--III-NP results of stored samples is largely determined by the characteristics of the assays. A single freeze-thaw cycle, storage of serum at 4°C for one day or at −20°C for up to 3 months does not result in a significant change in GH-2000 score. Verf.-Referat