A determination of the pre-analytical storage conditions for insulin like growth factor-I and type III procollagen peptide

Objective: IGF-I and type III procollagen (P-III-P) have been proposed as markers to detect GH abuse. This study aims to determine whether the pre-analytical storage temperature or delayed centrifugation affect the measured IGF-I and P-III-P concentrations. Design: Observational study. Setting: Wellcome Trust Clinical Research Facility, Southampton. Subjects: Nineteen healthy volunteers. Intervention: Blood was collected into bottles containing a clotting agent, lithium heparin or EDTA. One sample from each group was centrifuged and stored at -80 degrees C (control sample). The remaining samples from each group were stored as either serum or whole blood at 4 degrees C or room temperature for up to five days prior to storage at -80 degrees C. Outcome measures: IGF-I and P-III-P. Results: The storage temperature or timing of centrifugation did not appear to affect IGF-I concentration. In contrast, the Measured P-III-P concentration rose by 6.5-7% per day in clotted and lithium heparin samples when stored as whole blood (p < 0.006) or serum (6.2-6.5%, per day) at room temperature (p < 0.001), P-III-P did not change when the samples were stored at 4 degrees C. Although collection into EDTA inhibited the rise in P-III-P, the baseline measured values were significantly higher than in other media and spiking experiments demonstrated that EDTA exerted a significant matrix effect on the assay. Conclusion: While the optimum collection method is immediate centrifugation and storage at -80 degrees C, it would seem acceptable to store serum or clotted blood samples at 4 degrees C, but not ambient temperature, for LIP to five days. It is incumbent on the anti-doping authorities to provide facilities to allow this. (C) 2008 Elsevier Ltd. All rights reserved.