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

Holt, Richard I.G., Erotokritou-Mulligan, Ioulietta, Ridley, Sean A., McHugh, Cathy M., Bassett, E. Eryl, Cowan, David A., Bartlett, Christiaan and Sonksen, Peter H. (2009) A determination of the pre-analytical storage conditions for insulin like growth factor-I and type III procollagen peptide. Growth Hormone & IGF Research, 19 (1), 43-50. (doi:10.1016/j.ghir.2008.06.001).

Abstract

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 up to five days. It is incumbent on the anti-doping authorities to provide facilities to allow this

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Contributors

Author: Richard I.G. Holt

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