Establishment of Reference Intervals for Bone Turnover Biomarkers in Healthy Populations in Northern China

Aim: This study was intended to establish the reference intervals of bone turnover markers (BTMs) for healthy populations.
Methods: According to the Clinical Laboratory Standards Institute (CLSI) EP28-A3c, we recruited 774 healthy Chinese and investigated their clinical characteristics and relationships among gender, age, season and BTMs. The reference intervals of BTMs for healthy populations in Hebei of China were established through defining the central 95% range of all observations.
Results: We found that gender were associated with 25(OH)D, OC, β-CTX, and P1NP (P < 0.05), but not PTH1-84 (P=0.138). All serum BTMs showed differences among different age groups (P < 0.01). The level of 25 (OH) D in winter showed statistical differences with spring, summer, and autumn (P< 0.05). The OC level showed statistical difference between summer and winter (P=0.000). The P1NP levels showed statistical difference between spring and winter (P=0.019), summer and winter (P=0.000), and summer and autumn (P=0.012), respectively. The PTH1-84 levels in winter showed statistical differences with spring, and summer (all P=0.000), while there was no statistically significant difference in β- CTX levels between seasons.
Conclusion: We have established the reference intervals of several BTMs for healthy individuals in Hebei of China, which have statistical significance across different age groups and genders, and there are also significant differences between different seasons. Therefore, the Chinese medical laboratories in different locations should group individuals according to gender and age groups in different seasons, and establish corresponding biological reference intervals.

Keywords: 25-hydroxyvitamin D, 25(OH)D, osteocalcin, OC, β-carboxy-terminal cross-linking telopeptide of type I collagen, β-CTX, N-terminal procollagen of type I collagen, P1NP, parathyroid hormone 1-84, PTH1-84