Bone turnover markers are differentially affected by pre-analytical handling
Given that bone turnover markers are often shipped to central laboratories, it is essential to be aware of factors that will affect stability. We have evaluated how sample type, time before separation of blood samples, and time between separation and analysis affect the stability of four bone turnover markers.
Bone turnover markers are often shipped to central laboratories for analysis, which require knowledge of the stability of the markers of interest in different sample materials. The aim of the current study was to evaluate how time before separation of blood samples and time between separation and analysis affect the stability of four bone turnover markers in serum and plasma samples.
Serum, EDTA, and Lithium heparin (LiHep) plasma samples from seven osteoporosis patients and three healthy controls were collected and stored at room temperature for up to 72 h before separation and analysis. After separation, samples were stored at room temperature for up to 72 h and re-analyzed. The bone turnover markers N-terminal pro-collagen type 1 extension pro-peptide (P1NP), bone-specific alkaline phosphatase (BAP), C-terminal teleopeptide cross links of collagen type 1 (CTX), and osteocalcin (OC) were analyzed using the automated iSYS IDS platform.
P1NP and BAP were stable in both plasma and serum for 72 h before centrifugation. CTX levels were higher in EDTA plasma at all time points compared to LiHep plasma and serum. The use of EDTA plasma prolonged the stability of CTX as compared to LiHep plasma and serum. Osteocalcin showed high tendency to degrade in all sample types and concentrations were significantly lower after 24 h of storage.
For the bone turnover markers P1NP and BAP, the use of both plasma and serum is recommended. Samples for CTX analysis should be taken as EDTA plasma. Samples for osteocalcin analysis can be taken in either type of plasma or serum, but should be analyzed within 3 h or preserved at − 18 °C.
KeywordsBAP Bone turnover markers CTX Osteocalcin Pre-analytical P1NP Stability
Compliance with ethical standards
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study, formal consent is not required.
Conflict of interest
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