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Updated: Jul 3, 2026
A Quantitative Assay for Insulin-expressing Colony-forming Progenitors
Published on: November 28, 2011
A determination of the pre-analytical storage conditions for insulin like growth factor-I and type III procollagen
Richard I G Holt1, Ioulietta Erotokritou-Mulligan, Sean A Ridley
1Endocrinology and Metabolism Sub-Division, Developmental Origins of Adult Health and Disease Division, School of Medicine, University of Southampton, Southampton General Hospital, Southampton, United Kingdom. R.I.G.Holt@soton.ac.uk
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.
