ECTS Abstracts (2015) 1 P282

Impact of Freezer Failure on Bone Marker Stability During Serum Sample Storage

Yannick Lhoste, Philippe Vergnaud, Kafui Agbokou, Emeric Chassaing & Tanja Schubert


BioClinica LAB, Lyon, France.


Bone turnover markers are frequently used as pharmacodynamics biomarkers in clinical studies. Serum samples used to assess bone markers are collected at clinical sites, frozen, and subsequently sent to central laboratories in polystyrene boxes on dry ice. Upon arrival, serum samples are stored in −70 °C freezers before being measured in batches. We investigated the stability of the bone markers CTX-I (carboxy-terminal telopeptide of type 1 collagen), PINP (aminoterminal propeptide of type 1 collagen), Osteocalcin, measured on Modular E170, Roche Diagnostics and BSAP (bone-specific alkaline phosphatase), measured on Access II, Beckman Coulter, after a simulation of freezer temperature increase caused by power or equipment failure. Several aliquots of six different serum pools were stored in a full −70 °C freezer for 20 days. Then, electricity failure was simulated and the resulting temperature increase was monitored over the following 60 hours. One aliquot of each serum pool was taken out of the freezer after 8, 24, 32 and 60 hours respectively and refrozen at −70 °C until analysis.

Mean values ng/mlBaseline (−75 °C)8 hrs. (−53 °C)24 hrs. (−45 °C)32 Hrs. (−10 °C)60 hrs. (+4 °C for 1 hr.)
CTX-I (p results)0.4620.462 (1.0)0.459 (0.92)0.461 (0.68)0.459 (0.20)
P1NP56.0556.08 (0.83)56.01 (1.0)56.76 (0.40)55.49 (0.83)
OC27.5927.85 (0.92)27.63 (0.68)28.14 (0.53)28.15 (0.17)
BSAP13.7013.93 (0.40)13.51 (0.83)13.63 (1.0)13.64 (1.0)

No statistical difference (Wilcoxon test) was observed for the 4 bones markers tested between baseline samples and the follow-up samples at 8, 24, 32 and 60 hours. In conclusion, freezer temperature failure over 60 hours does not affect the validity of the data generated for the 4 bone turnover markers tested.

Disclosure: The authors declared no competing interests.

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